The smartest and most functional designs are often the simplest and the Piorama Adjustable Bag, that riffs on the classic duffel, epitomizes that philosophy. Three different sized bags--31L, 46.5L and 62L--in one, with three ways to carry--backpack straps, handles, or shoulder straps--it also packs down to the size of a football. Forged from technical nylon for strength and weather resistant, the main compartment is lockable, too.