A backpack is in its simplest frameless form, a fabric sack carried on one's back and secured with two straps that go over the shoulders, but it can have an external frame, internal frame, and there are bodypacks.
Designed with the modern athlete in mind, the Phase Backpack is both stylish and functional. The classic design features a roomy main compartment that opens via a two-way zip and padded adjustable straps so you can go through your day in style and comfort.