Compared: 1. Model 15.6inch: NO USB, with padlock 2. USB 15.6inch: with USB, with padlock 3. USB Upgrade: with USB, with padlock, with expandable structure Feature: 1. Selected splashproof high quality material 2. Anti theft double layers zipper, Anti theft free padlock 3. Large capacity, Earphone hole design 4. External USB charging port, only USB port, power bank not included 5. Expandable structure design: only "Upgrade" including 6. 17 inch vacuum backpack for T-B3143. There is a USB external interface, vacuum function, and vacuum pump. No expansion function. 180 ° flip cover opening. Larger capacity, more suitable for travel. Please Note: The payment of import duties is the obligation of every citizen. The exact charges are based on the customs import policies of different countries. It's  not allowed that the rejection of parcels and opened disputes due to tariff issues. If you want to know more about "Black USB Upgrade", just click the photo: