Black Diamond Size Chart Built for rough trails, big mileage and maximum comfort over the long haul, the Black Diamond Mercury 55 Backpack combines classic backpacking features with sleek, modern designs and unparalleled freedom of movement. Ideal for weekend trips from Olympic National Park to the Smoky Mountains, The Mercury 55 features Black Diamond's ergoACTIV XP suspension system that uses a custom, 3D pivoting hipbelt with urethane tendons, a men's-specific fit and SwingArm shoulder straps for increased stability and dynamic load transfer. The pack's front zippered panel gives you full access to the inside, while multiple pockets, dividers and straps help secure and organize your gear during extended trips. Features: - ergoACTIV XP suspension with OpenAir(TM) backpanel and SwingArm shoulder straps - 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 - Volume: [M] 55L (3,356 cu in), [L] 57L (3,478 cu in) - Average Stock Weight: [M] 2,100g (4 lb 9 oz), [L] 2,140g (4 lb 11 oz) - 400d polyester twill, 420d nylon twill - Please note that the swivel hip belt does not come attached, to attach use the allen wrench provided in the hip belt pocket. - Last Chance: Discontinued Style