18 Hour Posture Bra 100% Cotton Cup, Cushion Strap, Cushion Strap fiberfill: 100% Polyester. Side frame, Back: 86% Nylon, 14% Lycra spandex. Back support panel: 100% Cotton. Cushion strap lining, Cup lining: 75% Cotton, 25% Polyester. Exclusive of other trim and elastics. Back Support System that promotes better posture. Sheer mesh fabrics and cotton back panels Hidden front closure; cushioned adjustable straps. Machine wash warm water with like colors. Only non-chlorine bleach when needed. Machine dry low heat. Do Not Iron.