This is a device that attaches to a faucet and provides hot water instantly. It seems to be compatible with almost all faucets, but there may be some that it doesn't fit. I don't know the specifics. I installed it once, tested the power and water flow, and used it. I used it once, but the faucet in my house is positioned too low, and there wasn't enough space to use it, so I gave up. It's convenient because it provides hot water instantly where there wasn't any before. It's used, and I don't know about compatibility, so please consider purchasing at your own risk. It is not a water purifier. Winter, cold weather対策, cold wave, midwinter