Osprey knows that anything can happen when you're out on the trail and in case you find a way to bust the reservoir in your Seral lumbar pack the Hydraulics Lumbar 1. 5L Reservoir is there to replace it as a quick low-bulk hydration option when you're out on the trail. Whether you're running hiking or riding you'll appreciate all of its handy features both when you're filling up and on the move. A carry handle makes it easy to hold when you're filling it up while the PourShield collar extends vertically for easy and secure filling. The Slide-Seal closure system keeps a watertight seal when you're bouncing around on the trail and a hose with a bite valve provides smooth water flow with an easy twist on/off switch.