【Expandable Design Travel Bag】Before extended is 28L, dimensions are 17.7x13x4.8inch; 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 Approved】The overall size meets the size standards of the aircraft, and the portable zipper opening facilitates you to quickly pass the airport security check. 【Durable Backpack】Travel 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. 【Anti-theft Multifunctional Backpack】There 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. 【USB Charging Port】With built-in charging port enable to charge your phone anytime and anywhere. 【Multi-compartment Design & Wet Bag】Main pocket x 3, laptop compartment x 2 (fit for a 15.6” tablet and 17” laptop respectively), and many other pockets for different purposes. The wet bag is made of high-density water-resistant material that can help you to separate dry items and wet items, if you have wet clothes or a towel, you can put it in the wet bag. A separate shoe compartment can help you carry and keep your shoes better in your travel bag. 【Our Service】: If you are not satisfied within 30 day, you can get an unconditional refund. If you have quality problems within one year, you can contact us. We will respond to your request and after-sales within 24 hours.