Features ErgoACTIV XP suspension with OpenAir backpanel and SwingArm shoulder straps Top-loading with floating top pocket Waterproof taping on top and bottom Compartment divider, side and hipbelt pockets, front and internal organizer pockets Retractable trekking pole/ice axe loop, sleeping pad straps, hydration compatible Description Product Description DECENT FEATURES of the Black Diamond Mercury 55 Pack ErgoActiv XP suspension with OpenAir back panel Top-loading with floating top pocket, plus front zippered access Waterproof taping on top and bottom Compartment divider, side and hipbelt pockets, front and internal organizer pockets Retractable trekking pole/ice axe loop, sleeping pad straps, hydration compatible Also available as women's-specific Onyx The SPECS Material: 400d polyester twill 420d nylon twill The SPECS for Medium Volume: 3356 cubic inches / 55 liter Average Stock Weight: 4 lbs 9 oz / 2.10 kg The SPECS for Large Volume: 3478 cubic inches / 57 liter Average Stock Weight: 4 lbs 11 oz / 2.14 kg