This 3-liter hydration pack fits in place with two adjustable bottom straps, for maximum attachment versatility. One strap wraps around the seat and the other anchors to your frame. Attach in whatever position best suits your situation.
The main area of the pack is 7.5 inches wide and 14 inches tall (19 by 36cm). This is generously sized for most 3 liter bladders. If you're not carrying a bladder, or your bladder isn't full, there is room for other things like a jacket.
This pack is very versatile and made to go on nearly any recumbent seat. There needs to be some place near the top and the bottom of the seat for a strap to wrap around and that is about all. If you have a smooth topped mesh seat with nothing available for a strap to use, we make a Gear Belt that attaches around the top of the seat and lets you attach all sorts of things to the back of your seat.
This bag is generally not recommended for hardshell and narrow mesh seats, though it can be adapted to be used there. Another system, the 70LS/Double Century, is made for seats like these.