Arundel's Dual Seatbag is pretty straightforward it carries two tubes thus, 'double', two CO2 cartridges, an inflator, and tire levers everything you need to get your bike back up and rolling in the event of a flat. Like everything Arundel makes, though, the devil's in the details. There's a single strap the secures the bag around your saddle rails, and it holds quite firmly, negating the need for the all too common seatpost strap that inevitably wears through your bib shorts. In addition, Arundel reinforced the point of the bag where it contacts your seatpost bolts with a small leather patch, so your post won't wear holes in the bag. The zipper is large, and has an easy to grab pull, a little thing we appreciate when wearing full gloves.