These are inner socks from WEEZLE. Made of a down-like material, they are excellent as drysuit innerwear when diving in low water temperatures! The size is free, but I wear a 27cm shoe size and they fit with room to spare. I've used them about 40 times over 4 years, so there's some wear and tear, but they still have plenty of life left. I believe I bought them for around 25,000 yen, so I think you'll find them a good deal. Enjoy comfortable diving!