Nike Hydrastrong: 53% Polyester - 47% PBT 100% Polyester front lining Interior drawcord Flat seams Long-lasting durability Blaze your own path in the new Nike Hydrastrong Solid Brief! This extremely durable essential features an interior drawcord for adjustability, an internal front lining for comfort, and flat seams to reduce chafing. The Nike Hydrastrong fabric ensures long-lasting durability and chlorine resistance. No matter how hard you train, be confident that your suit works harder.