We made cute swim diapers because, wow, somebody had to. Outer layer: 80% recycled nylon / 20% spandex Lining: 92% polyester / 8% spandex jersey Concealed water-resistant lining contains without absorbing or swelling Comfortable, snug fit around waist and legs Can be worn alone unless your pool requires a double layer. (Swim diapers of any kind are designed to contain waste, not liquids.) UPF 50+