The 31" Zipsak is an extra large 4-wheeled duffel that folds into a small, easy-to-store pouch. Ideal for longer trips, college, summer camp and ski trips, the 31" Zipsak packs a ton, and then stores away neatly until you're ready to hit the road again! Its dual-opening packing system features a large wrap around zippered opening, plus an easy access top zippered opening. Made from a durable nylon fabric, the Zipsak is tear-proof, water resistant, and ultra lightweight.