The Standard 18.5 Inch Outdoor Seat Cushion from Polywood features a simple, square design that attaches securely with fabric ties for a snug fit on most outdoor chairs. Hand-sewn with all-weather performance fabric over a foam and blended polyester fiber fill, the cushion resists moisture, salt, sun, mold, and mildew, and dries quickly after exposure to rain. It cleans easily with soap and water, making routine maintenance simple.