Revelate Designs Shrew Seat Bag 2.25L BlackRevelate Designs Shrew Seat Bag Black. The Shrew seat bag is a low profile roll top bag that fits pretty much any bike out there dropper posts included. It utilizes the indie rail straps and has an integrated bottom support to prevent any sag or sway. It holds just the right amount of stuff (jacket snacks) for a day ride. Indie rail straps tighten to each saddle rail independently resulting in greatly reduced sway Compatible with most seat posts