The Osprey Viper 13 Hydration Pack incorporates a Hydraulics reservoir,streamlined feature set and a simplified reservoir to pack interface.The tough and durable Viper is the perfect pack for recreational mountain biking, hiking or a run on the trail. Biostretch harness with built in magnet for quick bite valve attachment. Spacer mesh backpanel creates a lightweight, yet supportive and ventilated Airscape backpanel Stretch sternum strap with magnetic hose attachment Lightweight webbing Detachable webbing hipbelt with modified streight ergopull hipbelt closure Lidlock helmet clip Top zippered pocket for quick access Elastic sternum strap with magnetic bite valve attachment New hydration sleeve design with direct access zip for fast loading. Cell phone MP3 pocket on shoulder strap Blinker light attachment Reflective graphics Internal pump sleeves and tool pouch Heat embossed fabric sunglasses pocket Front stretch woven pocket 2 X side compression straps Top zippered slash pocket 3 L Hydraulics Reservoir Number of Pockets: 5 Material: 210 double rip 600D poly Size: 20 x 9 x 8 Weight: 1 lb. 3 oz. Capacity: cargo 793 cu in.