The Pro-Tech backpack comes with an external USB port so you can connect your peripherals to a battery pack (not included) and stay charged while out on the go. Just connect your battery to the included usb cord and store safely inside the backpack's main compartment. Then connect your peripheral with your own USB cord to the port conveniently located on the side of the backpack; you'll stay charged throughout the day. The spacious 20L interior of the bag features a laptop compartment with seatbelt material safety strap and hook and loop closure large enough for a 15" computer, a slip pocket and zippered pocket. The exterior has two zippered pockets on the front and a pass-through port for headphones. Side mesh pockets hold essentials and two side buckled straps help give this backpack ...