[36L-50L EXPANDABLE DESIGN]: The extra large carry on backpack with expandable feature gives you a spacious capacity experience. Normal state is 36L, dimensions are 20.1x12.6x8.7inch. after extended is 50L, dimensions are 20.1x12.6x11.8inch. You can expand the zipper and buckles according to your requirement [CONVENIENT & PRACTICAL]: Business carry on backpack has external USB port with built in charging cable. offering you charge your electronic device by your own power bank any time and anywhere. there's a luggage strap makes it fixed on luggage for easier carrying. The hidden anti theft pocket on the back side can protect you personal valuable item such as passport and wallet. " [DURABLE & WATERPROOF]: Travel backpack is made of water-repellent fabri and anti scratch material, effectively resist rainwater splashing, protect items from getting wet. The adjustable shoulder strap and backside with breathable mesh plentiful sponge pads can helps you relieve the stress from shoulder and back [MULTI-FUNCTION & FLIGHT APPROVED]: The carry on business backpack overall size meets the maximum size allowed by most airlines, fits under the seat and in the overhead bin in airplane. also the design of freely 180 degrees zipper closure making you go through the security check quickly [CONSTRUCTION & DEMINSION]: one separate laptop compartment size is 18.5x11.8inch fits 17.3 inch laptop. The main compartment can store 4-7 days travel gear such as clothes, shoes and daily supplies, perfect for business traveling, school, weekend getaway, daily commutes. This expandable not only a business backpack, but also a perfect business backpack, 17.3 inch laptop backpack, 50L flight approved carry on backpack, work backpack, casual daypack with sport charging port.