The standard STL chaise cushion is constructed with four layers of densified polyester fill, which helps retain the cushions shape after prolonged use. The material is a marine grade Sunbrella, which is mold and mildew resistant and is treated with a resin that makes it water repellent. The cushion secures to the furniture with three sets of self Velcro or ties depending on the lounger of your choice. We have dozens of standard sizes to fit your chairs.