The differences between the two side bags are subtle; they are both ultrasonically welded, 100% waterproof, and same 22-litres capacity. The distinction that can be seen is that the Super Light (SL) bag is one of the lightest panniers on the market weighing in at 650 grams, and is designed for those who want to save grams and travel fast - whether that be commuting or touring. The Ultra-Durable (UD) is the more robust of the two, constructed with thicker, tougher walls. It's hypalon construction means it will stand up to more of a rough ride and is suited to those who expect their bags to take a pounding. Fundamentally, SL is about speed and the UD is about durability. For more on this, click here to check out of our deep-dive video on our side panniers bags.