Thank you for viewing. This is a Clotz Boots hot water bottle. The size is M, and I purchased it for 18,000 yen. It can be used without any problems even when filled with hot water. It warms you up naturally from your feet, and I think it saves a lot of electricity. My mother used it about 4 or 5 times, but she has entered a facility, so I am selling it. I use a shorter one from the same manufacturer that goes up to the ankles, but I think this long type warms your ankles properly, and it's great for quickly warming your whole body. It's a beautiful item, but please understand that it is a used item.