This bag has many necessary functions, first under cover, there’s drawstring closure, front pocket has zipper, inner side near the back, has a pocket with zipper too. Outside two side-pockets, inner bag has two-side pouches too, for phone or power bank etc. Headphone hole; Built-in USB port. Second, inside bag, enought room, has special interlayer with velvet for laptop (15.6″) or let it empty because it occupy less space, left is main room can bear enough items. Bag straps soft with cotton, not hurt the shoulders, Bag material anti-water; Strong; Inner side has 2cm cotton elastic layer to keep back feel breath & reduce pressure from bag.