Backpack Suitable for 17/15.6″” laptops.(The upgraded version adds a side cup pocket and the fabric is thicker). The backpack has an expandable design. When you travel and need to carry a lot of clothes, you can open the expansion zipper, so that you can get a backpack with a capacity of about40L. The side of the backpack has a USB charging port, which is connected to the power bank, which can easily charge your mobile phone when you are on business and travel. PU coated fabric is soft and skin-friendly, but also better waterproof. When you are on business and traveling, you can put it firmly on your suitcase, very convenient.