Large Travel BackpackThis backpack is made of waterproof durable polyester, good air permeability and heat dissipation with two padded shoulder straps, offers lightweight carrying and of force reinforcement, relieve the pressure of your shoulders, and keeping cool when you carry it for a long time. And it is tough, firm and does not fade. Durable BackpackTravel backpack is made of waterproof durable polyester, good air permeability, and heat dissipation with two padded shoulder straps that offer lightweight carrying and force reinforcement, relieve the pressure on your shoulders and keep cool when you carry it for a long time. And it is tough, firm, and does not fade. Fastening: Zipper Travel Backpacks Expandable Design Travel BagBefore extended is 28L, dimensions are 17.7x13x4inch; after extended is 40L, dimensions are 17.7x13x8.7inch. You can expand the zipper and buckles according to your requirement. The luggage belt on the back allows be slid over the luggage tube, the backpack is very easy to carry, and it is great for 3-5dof days of daily travel. Carry on Backpack Flight ApprovedThe overall size meets the size standards of the aircraft, and the portable zipper opening facilitates you to quickly pass the airport security check. Anti-theft Multifunctional BackpackThere is a zipper pocket on the back of the bag, which can store valuables such as mobile phones and iPods, which are anti-theft and convenient. Multifunctional Daypacks Hybrid (Backpack/Duffle Bag/Shoulder Bag/Travel Bag) conversion. Can be used in several different ways. It can be served as an everyday backpa ck,spacious college bookbags, professional backpack for laptops, or daily use anywhere for weekend getaways.