High energy activity requires keeping hydrated thatrsquos why the viper backpack comes equipped with an integrated 25l hydraulicstrade lt reservoir so you can push yourself to the limit the reservoir is accessed via an asymmetric zip for quick and easy refills the reservoir incorporates 2 chevron welded baffles to help maintain shape when full and limit sloshing from the water osprey also solved the lsquowandering hosersquo issue by placing a magnet in the pack sternum strap a