1. [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 19.6x8.7x12.2inch. After extended is 50L, dimensions are 19.611.412.2inch. Our suggestion is 50L backpack more suitable for tall people, recommended 5.91 feet and above. 160 pounds and above people use, more suitable for men, because the backpack is large, suitable for 5-7 days of travel 2. [CONVENIENT & PRACTICAL]: Business carry on backpack has external USB port with built in charging cable. ing 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. 3. [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. 4. [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 ly 180 degrees zipper closure making you go through the security check quickly