The Viper 13 packs four more liters than the popular Viper 9, but it is so light and well executed youw ill barely notice the extra capacity- until you need to pack more gear, that is. The Viper series hydration packs from Osprey are designed for riders who aim to strike fast and travel light. These aren't your jam it all in and be prepared for every emergency type packs. Carrying a 2.5L Hydraulics™ reservoir and drinking system, the Viper 13 manages the water and the a fair compilation of essentials for a fast 4-6 hour ride. The Viper 13 weighs just over 20oz and wears like nothing when empty. Padding and control mechanisms are highly effective, yet minimalist- not bulky. Perfect for trail riding, endurance and gravel road, and even bike-packing or adventure rides when your frame packs carry the heavy loads.

Osprey's Hydraulics™ LT 2.5 liter hydration system has a magnetic sternum strap bite valve attachment for easy and controlled water use in any conditions. The long, low profile reservoir rides in a dedicated compartment in the Viper 9 for quick, easy refills and great support against the back panel. Twin-welded chevron baffles stabilize the water and maintain a flat profile no matter the water level. All Hydraulics™ systems are BPA-free, phthalate-free, and lead-free. All materials used in construction are certified food safe according to FDA and EU regulations. Keep you system clean and it will always provide fresh, safe drinking water.

The 13 liters of storage on the Viper 913 is slickly conceived. A front panel shove-it pocket has zippered organization to help gear accessible in an intuitive manner. Access your bulkier gear in the main compartment via the zippered front panel. You can slip small items into the dual side mesh or harness pockets. There’s even a scratch-free slash pocket for your shades. Pack light and smart and you will have all the essentials you need and none that you don't. Carrying the load is the combination of the BioStretch™ Harness and AirScape™ back panel. The lightweight harness employs die cut foam to provide an active and contouring fit. The open sections and the mesh covering allow for airflow to keep you as dry and comfortable as possible. The AirScape™ back panel has mesh covered, ridged foam that allows maximum ventilation while keeping the pack load close to the body. Combined with an Atilon foam framesheet that allows dynamic body movement while it spreads load across the entire back, the overall support and suspension system is both lightweight and highly effective.

Control is provided by a webbing belt that is 20mm tall. While it serves to stabilize the load during active riding, some may chose to remove it, eliminating extra material around the waist. Luckily it is designed for that. Further load stabilization is provided by dual upper side compression straps that allow you cinch down your load as you remove gear or deplete your water stores. Osprey has mastered the fine details of packs for all purposes and the Viper 13 features their simple but genius elasticized helmet toggle called the LidLock™ helmet attachment system for transporting this essential safety device. You also have a blinker light attachment strap found near the base of the front panel of the pack that allows for quick light attachment when you get caught in the dark.

When you need a little more gear nut aren't willing to be loaded down, Osprey delivers the Viper 13. Pack light, but smartly, and ride fast knowing you will stay cool and composed no matter what the trail or road throws at you.