Gregory,s commitment to providing the perfect fit is evident in the technology of the Z 55 Internal Frame Pack. It offers maximum comfort and durability with true ventilation across your back without sacrificing the positive load transfer of weight to your hips. A floating lid, exterior side pockets, dual waist belt pockets, and hydration compatibility are just a few of the features that add to the Z55,s long list of advantages. This highly technical pack loads from the top and all access horseshoe front zip allows you get the essential gear you need. Ideal for long weekends in the backcountry and gear heavy alpine overnights. Updated Crossflo Suspension Ventilated back panel Dual hydration ports and sleeve Side, bottom and top compression Dual quick access waistbelt pockets Exterior side pockets with pass through compression Water resistant zippers Top load access All access horseshoe front zip Dual axetool attachment points with secure carry under compression flaps Quick attach rain cover Removable top lid Sturdy 11m Eva foam harnesses Number of pockets: 3 Torso Length: S 16 18 , M 18 20, L 20 22 Material: 210 D Robic dynagin ,100D Robic GR shadowbox 200 D polyester oxford Size: na Weight: S: 3,1 lbs. 15 oz. M: 3 lbs. 4 oz. L: 3 lbs. 7 oz. Capacity: S: 3234 cu. in M: 3356 cu in. L: 3478 cu. in.