BXT Outdoor Waterproof 30L Shoulder Foldable Nylon Travel Backpack with Bottle Holders nylon Material: nylon(waterproof) Easy to folds up into small pocket. Unfold at the airport to avoid excess baggage charges. Two large side mesh pockets for water bottles or umbrella. large?capacity: 30L Dimension:15.75X9.8X4.7inches(unfolded) 7X7X1.5inches(folded