Cloth Diaper Covers (which are often called Diaper Wraps) serve the same purpose as rubber pants did years ago. They provide a waterproof outer for pre-fold & fitted diapers. Diaper covers are usually made of Laminated Polyester, Laminated Cotton, Wool, or Polar Fleece. Cloth Diaper Covers fasten with hook and loop (velcro) or snaps.