Do I Need a Voltage Converter for Japan if I'm Traveling from the US?

Quick Answer: Most US travelers do not need a voltage converter for Japan if their devices say INPUT: 100-240V, 50/60Hz. Phones, tablets, laptop chargers, camera chargers, USB-C chargers, and most modern travel electronics are usually in this category. Many two-prong US plugs also fit Japanese outlets directly.

Japan is unusual because its household power is 100V, which is lower than the US 120V system, not higher. That means Japan is not like Europe, Korea, or many 220-240V destinations where a 120V-only US appliance can be destroyed by over-voltage. In Japan, the bigger questions are usually plug shape, grounding, weaker performance from 120V-only heating devices, and whether your trip continues to a higher-voltage country after Japan.

The safest way to decide is simple: check the label on every charger or appliance before you pack. If the label includes 100V or 100-240V, Japan's 100V supply is inside the supported range. If the label says only 120V, 110-120V, or 120V 60Hz, you need to think more carefully about the device type, the city you will visit, and the rest of your itinerary.

The video above is a useful visual introduction to Japanese outlets. The rest of this guide goes deeper into the part most quick travel-adapter pages skip: why Japan's 100V system changes the answer for US devices, when a plug adapter is enough, and when a DOACE GaN charger or voltage converter actually makes sense.

1. Japan Power Basics: 100V, Type A/B, and Two Frequencies

According to the Japan National Tourism Organization, the voltage used throughout Japan is uniformly 100 volts AC. Japan uses two frequencies: 50Hz in eastern Japan and 60Hz in western Japan. JNTO lists western Japan examples such as Nagoya, Kyoto, and Osaka, while Tokyo and Yokohama are part of the eastern 50Hz side.

KEPCO gives the more technical version: Japan's basic household voltage is 100V, with the frequency boundary around the Fujigawa River in Shizuoka Prefecture and Itoigawa City in Niigata Prefecture. KEPCO also notes that some appliances cannot be used correctly across frequency areas, especially certain older appliances, motors, microwave ovens, fluorescent lights, and dryers.

For short-term US travelers, that frequency split sounds more dramatic than it usually is. A modern charger labeled 100-240V~ 50/60Hz is designed for both Japanese frequency zones. But if you bring older timing devices, motorized equipment, specialty audio gear, lab equipment, or medical devices, the label and manufacturer instructions matter more than the country name.

2. Why Japan Is Different from Most Voltage-Converter Destinations

A US-only 120V appliance plugged into a 230V European outlet is exposed to almost double its intended voltage. That is the classic travel warning behind most voltage-converter advice. Japan is different. A US-only 120V appliance plugged into a Japanese 100V outlet receives less voltage than it was designed for.

That does not mean every 120V-only device is automatically ideal for Japan. It means the failure mode is different. A basic heating device may heat more slowly. A hair dryer may blow weaker. A motor may run with less torque. A device with electronic controls may behave unpredictably if it was never designed for 100V. Japan is lower-voltage than the US, but lower is not the same as guaranteed compatible.

Japan Guide summarizes this well for travelers: some North American equipment will work fine in Japan, but certain equipment, especially heating appliances such as hair dryers, may not work properly or may even be damaged. That is why this guide does not give a one-word answer. Instead, it separates plug shape, voltage range, frequency, and device type.

For a simple resistive heating appliance, power roughly follows the square of voltage. A 120V hair tool used at 100V may receive only about 69% of its rated heating power, because 100 divided by 120, squared, is about 0.69. That is why a US hair dryer in Japan may blow air but feel noticeably weaker. This estimate is useful for basic heaters, but it is not a guarantee for devices with electronic controls, motors, sensors, or smart temperature regulation.

3. Plug Shape: Type A Is Easy, Type B Needs Planning

Japan uses Type A and Type B outlets, but the common travel experience is not identical to the US. WorldStandards describes Type A as a two-pin, ungrounded plug used mainly in the USA, Canada, Mexico, and Japan. Type B adds the third grounding pin. Japan Guide notes that Japanese outlets often resemble North American outlets, but many are non-polarized, ungrounded two-slot outlets.

If your charger has a two-prong US plug, it will usually fit a Japanese outlet directly. If your laptop power cord or camera charger has a three-prong Type B plug, it may not fit a two-slot Japanese outlet. That is a plug-shape problem, not a voltage-conversion problem.

The safety boundary is grounding. Electrical Safety First warns that some travel adapters are not suitable for appliances that require an earth connection. A lightweight adapter can help with many laptop chargers and double-insulated travel devices, but it should not be used to defeat the safety design of equipment that truly requires protective earth.

4. Read the Label Before You Pack

The device label is more important than the country. Look for the word INPUT on the charger brick, charging base, or appliance body. Electrical Safety First gives the key example: a dual-voltage appliance may show INPUT: 100-240V. Because Japan supplies 100V, that device does not need a voltage converter in Japan.

A plug adapter changes only the physical shape of the plug. It does not convert voltage, and it does not convert frequency. A voltage converter or transformer changes voltage, but it still has wattage limits, load-type limits, and sometimes waveform limits. That distinction is why the Japan packing answer should start with the label, not with a product recommendation.

5. Device-by-Device: What US Travelers Should Actually Do

The Japan answer changes by device category. A phone charger and a curling iron may both have US plugs, but they do not have the same electrical risk. Chargers usually contain universal switch-mode power supplies. Hair tools often use high-wattage heating elements. CPAP machines may be dual voltage, but they are medical devices where reliability matters more than convenience.

Phones, tablets, and laptops

For mainstream electronics, Japan is one of the easiest destinations for US travelers. The typical Apple, Dell, Lenovo, camera, and USB-C charger is designed for international input. If the label says 100-240V, Japan's 100V supply is inside the rated range. Your remaining decision is convenience: whether your plug physically fits, whether you need more USB-C ports, and whether your hotel room has enough outlets.

This is where a DOACE GaN travel charger can make sense. It is not acting as a voltage converter. It is a wide-voltage charger for compatible USB devices, helping you charge phones, tablets, earbuds, power banks, and many USB-C laptops from one compact charger. If you already have a wide-voltage charger with the right plug and ports, you may not need anything extra for Japan-only travel.

Hair dryers, curling irons, and flat irons

Hair tools are the category most likely to create confusion. In 220-240V countries, a 120V-only hair tool can be dangerous without a suitable converter. In Japan, the same 120V-only tool is not being over-volted; it is being under-volted. That may sound safer, but it often means poor performance. A hair dryer may feel weak, a curling iron may heat slowly, and a flat iron may not hold the temperature you expect.

Dual-voltage hair tools are different. If the label says 100-240V or includes a manual voltage selector with a 100V/120V range, the tool may be suitable for Japan when used exactly as the manufacturer instructs. If it is a high-wattage device, also check the plug, outlet, and hotel rules. Many hotels already provide hair dryers, and buying or borrowing a local-compatible tool is often simpler than carrying a bulky transformer for a Japan-only trip.

Electric toothbrushes and shavers

Do not assume every grooming charger is universal. Some electric toothbrush bases are wide voltage; others are regional. The label may be tiny and located on the underside of the charging base. If it says 100-240V, Japan is fine. If it says 120V only, the device may not charge correctly at 100V, and a simple plug adapter will not change that.

For short trips, the practical answer may be to fully charge before departure, use a USB travel charger if your model supports it, or bring a manufacturer-approved travel case. A voltage converter is rarely the first purchase for a toothbrush alone unless the device manual clearly supports external transformer use and the rating is understood.

CPAP and medical equipment

Many modern CPAP power supplies are labeled 100-240V, 50/60Hz, which covers Japan. But CPAP travel should be handled more conservatively than phone charging. Check the main power brick, humidifier, heated tube, battery charger, and any accessory power supply. If any component has a narrower rating, verify it before travel.

For CPAP, a plug adapter is not the same as a medical travel plan. Bring a backup mask part if appropriate, confirm airline battery rules if you use a travel battery, and ask the manufacturer whether a converter, transformer, or pure sine wave inverter is recommended for your exact model. Do not rely on a generic converter for a medical device unless the device manufacturer says it is acceptable.

Japanese 100V appliances brought back to the US

The reverse direction is easy to overlook. A Japanese appliance bought in Tokyo may say 100V only. Bringing that device to the US exposes it to a nominal 120V supply, which is higher than its rating. That is a different problem from bringing a US appliance to Japan. For a 100V-only Japanese rice cooker, beauty tool, audio device, or collectible appliance, you may need a US-to-Japan step-down transformer sized for the device's wattage and load type.

If you plan to buy electronics in Japan, check whether the product is sold as an overseas model with 100-240V input. Many tourist-oriented stores carry international models, but domestic Japanese models may be 100V-only. A bargain is not a bargain if it needs a heavy transformer at home or cannot be used safely.

6. Does Japan's 50Hz/60Hz Split Matter?

Japan is one of the rare countries where household voltage is nationally consistent but frequency is split by region. Eastern Japan, including Tokyo and Yokohama, uses 50Hz. Western Japan, including Nagoya, Kyoto, and Osaka, uses 60Hz. This split comes from historical development of the power grid, not from a traveler-facing plug difference.

For most modern travel electronics, the split does not change your packing list. A charger labeled 100-240V, 50/60Hz is designed for both sides of Japan. The same is usually true for many laptop power supplies, phone chargers, camera chargers, and USB-C power adapters. The label already tells you that both Japanese frequencies are acceptable.

Frequency becomes more important when the device uses a motor, timer, pump, compressor, or older transformer that depends on line frequency. KEPCO specifically notes that some appliances may not be usable across different frequencies or may have reduced efficiency. For travelers, this mainly affects older clocks, record players, kitchen appliances, certain grooming devices, and specialty equipment. If a device label says only 120V 60Hz, do not assume it will behave normally in Tokyo's 50Hz area.

7. Japan-Only Trip vs Japan Plus Other Countries

The biggest packing mistake is answering the Japan question without looking at the full itinerary. If you are flying from the US to Tokyo, Kyoto, and Osaka only, most wide-voltage electronics need no voltage converter. You may only need a compact plug solution for three-prong plugs, USB-C charging, or limited hotel outlets.

If your trip continues from Japan to South Korea, Singapore, Australia, Europe, or the UK, the answer changes. Those destinations commonly use around 220-240V. A 120V-only hair tool that merely runs weakly in Japan may be damaged in a 230V country if plugged in with only an adapter. Multi-country trips are where voltage-converter planning becomes much more important.

8. Real Travel Scenarios: Hotels, Trains, and Airports

Hotel rooms in Japan often provide Type A outlets, but older rooms may have limited outlet count and fewer grounded Type B receptacles. A two-prong phone charger may be effortless. A three-prong laptop cable may need a grounded outlet or a safe adapter choice. If you depend on a laptop for work, pack a compact solution before arrival instead of assuming every outlet will match a US three-prong plug.

For trains, treat onboard outlets as convenience power for small electronics, not as a guarantee for every seat or every device. SmartEX notes that on certain N700-series Shinkansen trains, outlets are available at all Green Car seats and at window seats or specific end-row seats in ordinary cars. That is useful for phone or laptop charging, but it does not replace checking your charger label.

Airports, cafes, and coworking spaces may offer outlets, USB ports, or charging stations, but public charging should be used carefully. A trusted charger plugged into an AC outlet is usually preferable to relying on unknown USB ports. If you carry several devices, a wide-voltage multi-port USB-C charger is often more useful in Japan than a bulky voltage converter.

For Japan-only travel, the practical packing list is usually: original wide-voltage chargers, a compact plug adapter if you have three-prong plugs, a multi-port charger if you want fewer wall bricks, and device-specific planning for hair tools or medical equipment. For multi-country travel, add a voltage plan for every single-voltage device before you leave the US.

9. A Practical Decision Workflow for US Travelers

If you want the shortest safe process, use this workflow instead of trying to memorize every plug standard. It works because it separates four different problems that are often mixed together: voltage, frequency, plug shape, and device load. A Japan outlet can look familiar to a US traveler, but that does not prove the device is electrically ideal. A device can be dual voltage, but that does not solve a three-prong grounding issue. A converter can change voltage, but that does not make every high-wattage or medical device compatible.

This workflow also prevents overbuying. A traveler with an iPhone, iPad, USB-C laptop, camera charger, and power bank may have five devices but zero converter need. Another traveler with one 120V-only curling iron and a Japan-Korea itinerary may have one device that changes the entire packing plan. The number of devices does not matter as much as the label and the load type.

10. What the Main Sources Agree On—and Where Travelers Misread Them

Several public travel and electrical-safety sources agree on the core Japan facts. JNTO states that Japan uses 100V and two frequencies. KEPCO explains the 50Hz/60Hz boundary and warns that some frequency-sensitive appliances may be affected. Japan Guide emphasizes that North American plugs may look similar but some equipment, especially heating appliances, may not work properly. Electrical Safety First separates plug adapters from voltage conversion and reminds travelers that a travel adapter does not change voltage or frequency.

The common misreading is to turn these facts into a simple yes-or-no rule. “Japanese outlets look like US outlets” becomes “everything US works.” “Japan is foreign” becomes “I need a converter.” Both are incomplete. The more accurate answer is: Japan is physically familiar, electrically lower-voltage than the US, and split by frequency, so the device label matters more than the plug shape alone.

Power Plugs & Sockets lists Japan as Type A/B, 100V, 50/60Hz, which is a helpful quick reference. But a quick reference cannot tell whether your hair tool has electronic temperature control, whether your CPAP humidifier shares the same rating as the main brick, or whether your three-prong laptop cord needs grounded power. Use these sites to confirm country facts, then use your device label for the actual decision.

11. When a Converter or Transformer Makes Sense in Japan

There are Japan situations where a transformer can make sense, but they are narrower than many travelers expect. A true 120V-only device may perform better with a transformer that supplies closer to 120V from a 100V Japanese outlet. However, that transformer must be designed for step-up use from 100V to 120V, must support the device wattage, must be suitable for the load type, and must be practical to carry. For many short trips, replacing the device with a dual-voltage travel version is easier.

High-wattage heating devices are the least travel-friendly. Hair dryers, irons, steamers, and some styling tools can draw hundreds or more than a thousand watts. A small travel converter is not automatically suitable for these loads. Even if a converter has a peak wattage claim, continuous wattage, startup behavior, duty cycle, ventilation, and device electronics all matter. If the hair tool is essential, a dual-voltage model or a local/hotel device is usually a better Japan-only solution.

Sensitive devices add another layer. Some electronics do not only care about voltage; they care about waveform quality, grounding, surge behavior, and stable operation over time. That is why pure sine wave discussions appear in CPAP and sensitive-device contexts. It does not mean every Japan traveler needs pure sine wave conversion. It means that if a device manufacturer requires clean AC power and permits converter use, waveform becomes part of the selection criteria.

12. Special Notes for Hair Tools and Beauty Devices

Hair tools deserve their own warning because they combine high wattage, heat, electronics, and personal routine. A label that says “dual voltage” is useful only if you understand how the tool changes voltage. Some tools automatically accept 100-240V. Others have a manual selector that must be set before plugging in. Some are sold in regional versions that look identical online but have different ratings. Check the physical tool you are packing, not only the product listing you remember.

In Japan, a 120V-only hair tool may not fail dramatically; it may simply disappoint you. That can be worse from a planning perspective, because you may not discover the problem until the morning you need it. If a styling tool is essential for an event, do a label check at home and decide in advance whether to bring a dual-voltage travel model, use the hotel dryer, or buy a local-compatible option after arrival.

For multi-country beauty travel, the risk increases sharply. A tool that merely underperforms in Japan can be unsafe in Europe or Korea if plugged into 220-240V with only a shape adapter. This is where many “Japan converter” searches are actually multi-country converter searches in disguise. If your trip includes Japan plus high-voltage regions, make the high-voltage country the planning baseline for single-voltage devices.

13. Special Notes for CPAP, Batteries, and Overnight Devices

CPAP users should treat Japan as manageable but not casual. Many modern CPAP supplies cover 100-240V and 50/60Hz, which is good news for Japan. But the main brick is only one part of the system. Heated humidifiers, heated hoses, battery chargers, and replacement power supplies may have their own ratings. If you use a travel battery, also check airline rules and charging requirements before departure.

The overnight nature of CPAP changes the risk. A phone charging slowly is annoying. A medical device failing overnight is a serious problem. If your label confirms 100-240V and 50/60Hz, you may only need the correct plug and outlet access. If any component is single-voltage or manufacturer guidance mentions pure sine wave power, do not improvise with a random converter. Contact the device maker or medical equipment provider before travel.

Hotel outlet placement can also matter. Some rooms have convenient outlets near the desk but fewer near the bed. Extension cords and power strips may be restricted, especially if they include surge protection or are not rated for local use. A compact, properly rated plug solution is safer than packing a US household power strip and assuming it will be accepted everywhere.

14. Pure Sine Wave: Only for Specific Sensitive-Device Cases

Pure sine wave is easy to misunderstand in a Japan power discussion. It is not a special feature that makes every US device work better in Japan. It is about the shape and cleanliness of AC output from a converter or inverter. Normal wall power is a smooth sine wave. Some travel converters create a modified sine wave or stepped wave, which approximates AC power but can be rougher for sensitive electronics.

For most Japan-only phone, tablet, camera, and laptop charging, you are not choosing between pure sine and modified wave at all. Your charger accepts Japan's AC input and internally converts it to DC output for the device. The charger label, not the external waveform marketing, is the main decision point. Pure sine wave becomes relevant only when you are actually using a converter or inverter to power a compatible AC device.

A smooth pure sine wave can reduce noise, buzz, heat, display flicker, or unstable behavior in sensitive compatible devices. CPAP accessories, certain medical-adjacent devices, audio equipment, and electronically controlled appliances are the kinds of products where waveform quality may matter. But this is not a magic compatibility pass. It does not override wattage limits, grounding needs, manufacturer restrictions, or the fact that some devices should not be used with travel converters at all.

The safest phrasing is: if a sensitive device requires AC conversion, if the manufacturer permits converter use, if the wattage is within the converter rating, and if clean waveform is recommended, then a pure sine wave converter can be the right category. If any of those conditions is missing, choosing pure sine wave does not solve the missing requirement. For Japan-only travelers with wide-voltage chargers, this section is mostly a boundary marker so you do not overbuy.

15. Converter Sizing and Load Type: Why Watts Are Not the Only Detail

If you do decide a converter or transformer is needed, size it from the device label, not from a guess. Look for watts (W), amps (A), or volt-amps (VA). If the label gives amps, multiply volts by amps to estimate watts. A device marked 120V 1.5A is roughly 180W. A device marked 120V 10A is roughly 1200W. That difference determines whether a compact travel converter is realistic or whether the appliance belongs in the “do not travel with it” category.

Continuous wattage matters more than short marketing claims. Some devices also have startup surge. Motors, pumps, compressors, and some heating tools can draw more current at startup or during temperature cycling than their steady-state number suggests. A converter that appears large enough on paper may still shut down, restart, run hot, or trigger protection if the load type is wrong. That is why compatibility language should say “compatible devices within rating,” not “any appliance under a headline wattage.”

Japan's 100V supply makes sizing more nuanced because the common US-to-Europe over-voltage panic is not the main problem. If your device is 120V-only and low wattage, you may ask whether you need a 100-to-120V step-up transformer for performance. If the device is high wattage, you should also ask whether carrying that transformer makes sense. For many hair and heat appliances, a destination-compatible or dual-voltage device is lighter, simpler, and safer.

16. Bringing Japanese Electronics Home to the US

Japan shopping adds a second electrical question to your trip. A US traveler may arrive with wide-voltage chargers and no converter need, then leave Japan with a 100V-only appliance. Domestic Japanese rice cookers, beauty devices, audio equipment, specialty kitchen tools, and collectibles may not be designed for US 120V. The plug may fit or almost fit, but the voltage rating is still wrong.

If the product label says 100V only, do not assume the US 120V difference is small enough to ignore. A 20% voltage increase can raise heat and stress in devices that were not designed for it. For heating appliances, the power increase can be significant. A properly sized step-down transformer may be required, and for high-wattage appliances that transformer can be heavy and expensive. Always compare the transformer cost and convenience with buying an overseas model.

Tourist-focused electronics stores in Japan sometimes sell overseas models marked for 100-240V or multiple regions. Those are usually easier for US travelers. Ask staff for the international version, check the label yourself, and keep the manual. If a product is domestic-only, factor the transformer into the real total cost before buying.

17. Where DOACE Products Fit—and Where They Do Not

For Japan, the honest product route is not “everyone needs a converter.” Most US travelers with wide-voltage electronics need a plug and charging plan, not voltage conversion. A converter becomes relevant when the device is single-voltage, the trip includes 220-240V countries, or a sensitive device needs a specific output type. Use the table below before choosing a product.

18. Common Mistakes to Avoid

• Mistake 1: buying a voltage converter for every Japan trip. If your devices say 100-240V, a converter is unnecessary for Japan's 100V supply.
• Mistake 2: thinking a plug adapter converts voltage. It only changes plug shape. It does not change 100V, 120V, 230V, or frequency.
• Mistake 3: ignoring the third grounding pin. A three-prong plug may not fit a two-slot outlet, and grounding should not be casually defeated for equipment that requires it.
• Mistake 4: testing a 120V-only hair tool for the first time on the trip. In Japan it may run weakly; in a later 230V country it may be unsafe without a proper converter.
• Mistake 5: forgetting the return direction. Japanese domestic 100V appliances may need a step-down transformer in the US.

Japan Packing Checklist

Before you close your suitcase, make a small device list and mark each item as “wide voltage,” “120V-only,” “unknown,” or “buy/use locally.” This takes five minutes and prevents most Japan power mistakes. Put phones, tablets, camera chargers, laptop adapters, power banks, and USB-C chargers in the wide-voltage column only after you physically see 100-240V or 100V on the label. Put hair tools, toothbrush bases, shaver chargers, CPAP accessories, and any older appliance in the check-carefully column until you verify the exact rating.

For a Japan-only trip, your final packing list will often be surprisingly light: one or two wide-voltage chargers, a compact plug adapter for any three-prong or awkward plug, charging cables, and device-specific backups for medical or work-critical gear. For a Japan-plus-high-voltage itinerary, add a second checklist line for each next country. The device that is merely weak at 100V may become unsafe at 230V, so do not let the easy Japan portion hide the harder part of the trip.

If a label is missing, damaged, or too small to read, do not guess based on plug appearance. Search the exact model number, check the manufacturer's manual, or replace the charger with a known wide-voltage option before travel. For critical devices, carry proof of the rating in a photo on your phone. That way, if you need to buy a replacement cord, adapter, or charger in Japan, you can compare the required input and output instead of relying on store packaging alone.

Also separate “must work” devices from “nice to have” devices. A laptop charger for remote work, a CPAP setup, or a camera battery system for a paid shoot deserves backup planning. A steamer, old toothbrush base, or single-voltage styling tool may be easier to leave at home. Japan's 100V system is friendly to many modern electronics, but the best travel setup is the one that removes uncertainty before you reach the hotel room.

FAQ

Can I plug my US phone charger directly into a Japanese outlet?

Usually yes, if the charger label says 100-240V, 50/60Hz and the two-prong plug physically fits. If you have a three-prong charger or need more ports, bring a suitable adapter or wide-voltage charger.

Do I need a step-down converter from 120V to 100V?

Most travelers do not. Many US electronics already support 100V input. For a 120V-only appliance, a 120-to-100V transformer may improve voltage matching, but it must be sized correctly and may not be worth carrying for a short trip.

Will my US hair dryer work in Japan?

It depends. A dual-voltage model that includes 100V or 100-240V may work when set correctly. A 120V-only dryer may run weakly on 100V. Hotel hair dryers or local-compatible tools are often easier for Japan-only travel.

Is Japan 110V or 100V?

Japan is generally listed as 100V, not 110V or 120V. Some travel pages use loose language because Japan and North America have similar plug shapes, but the official voltage information from JNTO and Japanese utilities is 100V.

Does the Tokyo 50Hz frequency matter for laptop chargers?

Not if the charger says 50/60Hz. Most modern laptop chargers do. It matters more for older motors, clocks, timing devices, and specialized equipment labeled for only one frequency.

Can I use a Japanese 100V appliance in the US?

Not directly unless the appliance label includes 120V or 100-240V. A 100V-only Japanese appliance may be over-volted on US 120V power and may need a properly sized step-down transformer.

Final Recommendation

If you are traveling from the US to Japan, do not start by shopping for a voltage converter. Start by reading labels. For devices labeled 100-240V, pack a plug/charging solution. For 120V-only hair tools, motorized devices, or medical equipment, check the manual and be realistic about performance at 100V. For multi-country trips that include 220-240V destinations, plan converter needs before you leave.

For most Japan-only travelers, the smartest DOACE choice is a compact wide-voltage GaN charging setup for everyday electronics. For single-voltage appliances or sensitive equipment on broader international trips, choose a converter only after confirming wattage, waveform, grounding, and manufacturer compatibility.