Purchased at Costco. Only tried on. After that, it was hung on a dog hanger and stored at home. I am selling it because the size didn't fit. It's made of a material that can be wetted with water to keep cool. Size: 4 Please refer to the size chart on the website. I am an amateur, and there are also individual differences depending on the dog breed, so I can only answer questions to the best of my ability m(_ _)m Please purchase only if you understand the above. Please refrain from purchasing if you are nervous or concerned about minor details, as this is a used item. Yu-Yu ↔︎ Mercari delivery Changes are possible.