It is also good looking comfort. Since it is the bottom of urethane, it has a slip prevention effect and it is solid. It is soft and comfortable to make by firmly supporting the instep of the foot. The structure is simple, it seems easy to wash because it is slippery, it may be hygienically good. Just because I opened the box for a while, I think that it is the smell of rubber in the inside but because it has a very strange smell (smell of feet like someone wore)? Is it? Without this it would be better.