Expandable Large Capacity: Compressed capacity of 23L, full-expansion zipper creates 30% percent more packing space, capacity up to 40L, total three layers. The first compartment can store your phone, passport or other small items etc. The second compartment can store clothes and daily supplies. The third compartment is a laptop compartment, which can store a 17.3 inch laptop as well as 15.6 inch, 14 inch and 13 inch Laptop. USB Charging Port Design: The usb backpack comes with a charging port you can link your phone to and easily charge during outdoors and travel. Place your power bank inside the bag and connect your phone to the outer port (built-in charging cable inside)