Waist measured flat: approximately 36cm. (Please note that there may be slight variations due to amateur measurements.) It stretches well because it has elastic. There's a zipper on one side of the waist. Please check the photos. I've registered the size as L, but it's a 【②】 in HOTPING sizing. I've registered it as L because I was able to wear it with my usual L size. Since it's a used item, please purchase only if you understand. Also, it will be shipped in simple packaging.