Osprey Packs Rev 18 Hydration Pack 2.5 liter hydraulics lt reservoir included providing on the go hydration A stretch body Wrap harness is designed to move with you during high Activity endeavors A reverse Spacer mesh back panel provides a soft, irritation free contact surface for the ultimate in back panel comfort and high Activity performance The Rev bio stretch body belt featuring stabilization wings is designed for stability and comfort during high Activity endeavors A removable Drop down Digi flip media pocket provides secure storage and Quick access to all manner of touch screen mobile devices