Features Enter your model number above to make sure this fits. P.when("RPPStripeRendered").execute(function(stripeData){ if(stripeData && stripeData.state){ switch(stripeData.state){ case "result-found": document.getElementById("replacementPartsFitmentBulletInner").innerHTML = "This fits your "+stripeData.item+"."; document.getElementById("replacementPartsFitmentBullet").className = ""; break; case "no-result": if(stripeData.showBullet && stripeData.showBullet !== "0"){ document.getElementById("replacementPartsFitmentBulletInner").innerHTML = "No information found for this part for "+stripeData.item+"."; document.getElementById("replacementPartsFitmentBullet").className = ""; } break; default: document.getElementById("replacementPartsFitmentBullet").className = ""; } } }); Material: [main] 210D polyester, [accent, bottom] 420D nylon packcloth Volume: 549 cu in Support/Suspension: Atilon foam Shoulder Straps: padded Waist Belt: yes Description Product Description Whether it's an epic relay race, stiff hiking trail, or challenging cross country ride, trust Osprey's Viper 9 Hydration Pack to satiate your thirst-quenching needs. The ventilated Airscape back panel and perforated Biostretch harness not only keep the pack from shifting around during fast-paced pursuits, but it also maintains comfort even when you break a sweat. Additionally, the three-liter Hydraulics Reservoir is shaped to match the contour of the back panel--which means better balance and less sloshing. And to ensure maximum preparation for bike-related break downs or unexpected detours on your hike, Osprey added a large zippered main compartment (in addition to the hydration sleeve) where food, layers, spare tubes, and tools can be carried while the two front pockets make it easy to stash a light rain jacket or trail map for quick access.