Happy flute swim nappies are great for the pool. They do not require an insert as the snug fit, pul outer and mesh lining ensure any solids are contained. One size fits most: from 3 to 15 kilos approximately.Elastics waist and legs to provide a secure and stretchy fit. Outer: waterproof 100% polyester with pul, designed for holding solids. Inner: polyester mesh (easy to clean up, offering comfort against baby's sensitive skin). Use: adjust to fit baby. A snug fit on the legs and waist areas are key to avoid leaks.