Soft and Breathy: 100% Jersey Cotton Ely's & Co.'s Pack n Play | Mini Crib Sheet Sets are composed of light, soft and breathable fabric. Made from 100% high quality Jersey knit cotton, babies love our crib sheets, as they offer a soft, welcoming texture that lulls them into restful sleep. Adaptable Elasticity: Fits Multiple Mattress Sizes Our exceptional product fits all standard mattresses sold for Pack n Plays, Mini Cribs an Porta Cribs, enabling a great fit on irregular sized mattresses. Our uniquely designed sheet set is equipped with flexible, generous elastic, easily covering your mattress while simultaneously offering a tight seal, enabling a great fit for your mattresses.