A good, solid duffel bag is a mainstay for many travelers — especially those who like packing up a car for a weekend away, or frequent flyers who disdain the thought of checking a bag. Peak Design introduced its own take on the duffel bag this year, with a couple of different twists on the concept. The Peak Design Travel Duffel 35L is the most fundamental of the company’s options, and it delivers a lot of packing space and support for Peak’s packing tools if you want to get real serious about space optimization.