Aircast Replacement Sock Liner for Aircast Walker Brace/Walking Boot Intended to help reduce skin irritation while wearing an foot brace or walking boot Compatible with the following Aircast Walker Braces / Walking Boots: XP, FP and SP models Full length, stretch tube sock measures 22 inches long Closed-toe sock is made with a cotton/polyester/lycra spandex blend Includes 1 white sock liner; One size fits all