EXTERNAL USB INTERFACE: 1.Simply connect your power bank(portable charger) with the built-in USB extension cable inside the backpack 2.make your external USB cable connect with the external USB port , then it can charge your tech electronic device.This cool backpacks is suitable for a variety of occasions such as daily working, school, travel, climbing, hiking and cycling. SIZE: 12.6 "* 16.5" *7.1 "(WxHxD). HIGH CAPACITY: 40L. WEIGHT: 1.75 lb. The main inner bag can accommodate notebook computers of 15-15.6 inches, A4 size magazines, umbrellas, cameras, wallets, clothes,etc. Inside the backpack, it also provides built-in computer compartment and pockets for pens, cell phones and documents. Soft sponge is applied in this part so as to protect your computer from collisions better. ANTI THEFT FLIP-TOP DESIGN : with two tight buttons , it securely hides the inner bag zipper , which cannot be unzipped without unbuttoning the Flip-top first . Owing to this , any theft behaviour will alert you to notice when thieves are trying to open the backpack. Super reliable and safe compared to ordinary backpacks.EXTERNAL ZIPPER POCKET allows you to retrieve items by one hand, without the need to take down the bookbag completely, providing you the best convenience DURABLE REINFORCED MATERIAL: high-quality Oxford Fabric which is waterproof, anti-scratch and friction resisting, combined with soft and comfortable Polyester Lining material . All leather zippers have passed laboratory fatigue strength tests for simulation under actual using circumstances. Reinforced metal shoulder strap buckles are able to withstand more weights . What You Get: 1x Backpack，1x Built-in USB CABLE NOTE:NOT INCLUDING Power Bank or original phone usb cable