The inside of the hat is treated with a cooling process that makes it cold when wet, wrung out, and shaken. It has an elastic cord and stopper around the neck, allowing you to adjust the size to fit your dog. Quoted from the product page ⤴︎︎︎ I purchased this around last summer, but it didn't suit my dog very well, so I only used it once. A 2.3kg toy poodle wore it. Dog, Dog hat, Hat, Solgra, Checkered pattern, Purple