The Charlie Banana® award-winning, stylish and secure Reusable Swim Diaper is ingeniously made of one waterproof layer and one ultra soft and absorbent Lyocell fabric layer. This product's other uses include underwear, bloomer, and a potty training accessory. Indoor and outdoor use - Day use only. We proudly support the US Swim School Association. Reusable Swim Diaper are mandated in many swim schools and public schools as disposable swim diaper are not very efficient at contaning accidents.