The Stuff Sack organizes the inside of your dog bed duvet cover contents, making it easy to use old blankets, pillows, and clothing--all while keeping stuff out of landfills! When it's time to clean the inside of your dog bed, simply throw the Stuff Sack and all of its contents directly into the washer. The Stuff Sack is made from 100% nylon, fully-zippered and gusseted for extra strength and style. Sold separately from the coordinating duvet covers, it comes in four sizes.