The incredibly versatile Piorama Adjustable Bag, available in six colors, is an innovative duffel that riffs on the iconic 1950s U.S. military bag. The big difference with this near half-the-weight offering (1.4lbs) is that it expands from a 31-liter to a 62-liter bag (with a 46.5-liter option in between) and can be easily converted to a backpack thanks to some added straps.