Scalable capacity : size: 17.7 x 12.6 x 4.7~8.7 inches, capacity: 20L~35L. weight:1.1~1.3KG. Notebook compartment can hold 15.6 inch laptop(Laptop pocket size: 15.7 x 11 x 1.2 inches). Waterproof Hard Shell : The surface is PC and ABS Material,Very hard, waterproof, scratch-resistant . The zipper part is also waterproof. Both sides of the backpack can be unfolded 180°. Notebook and personal belongings will be protected dry. TSA Anti-Theft : TSA double anti-theft lock design. Luggage belt design. hidden card bag on the shoulder strap to protect your valuables from thieves. Very suitable for international air travel and day trips. USB Charging Port : 2This USB backpack has an external USB charging port and an internal charging cable, which provides a more convenient way for you to charge your phone while walking. (Note: User needs to prepare power bank .) Ergonomic design: Adjustable chest strap and non-slip, breathable S-shaped mesh shoulder strap makes you feel comfortable and not tired. The 3D honeycomb breathable backrest can reduce the stuffiness of the back. Oxford fiber and polyester material makes it more durable.