(20 inch head circumference) Knit fabric. Arrives complete with matching face mask as shown. The face mask is adjustable and washable. Please Note: These masks are not designed to be used in a medical setting. The set arrives complete with the matching face covering mask shown. If you have been seeking a cap that stays on your head, your quest is over. The secure tie feature ensures it stays on. If you are thinking, that is amazing..you should know it's also comfortable too. Best of all you can tie it off based on what feels comfortable for you. (fits up to standard 20 inch circumference around the head) Ships priority mail to addresses in the U.S.