Interior drawcord at waist for a snug, adjustable fit Durable, chlorine-resistant performance polyester for streamlined shape and color retention Fully lined for comfort Hand wash Fabric: Body: 100% polyester. Lining: 90% polyester/10% spandex. The Nike Poly Core Solid Men's Swim Briefs are designed with chlorine-resistant stretch fabric for durability and a snug, comfortable fit during long training sessions in the pool.