The Osprey Seral 7 Lumbar Hydration Pack is designed to go fast. Osprey\'s bike-specific lumbar-pack featuring an internal hydration reservoir.If you prefer a hydration solution on your back instead of a bag to carry over the shoulders, the Osprey Seral 7 Lumbar Hydration Pack is for you. There are many luxuries that we can do without on a mountain bike, but water is not one of them. The Seral 7 is designed to carry the 1.5L hydration bag included with the magnetic valve mouthpiece that attaches to the hipbelt for easy access while pedaling. Compression straps adjust the pack to your lower back and wrap around your hips for supreme stability, even on technical terrain. Some lumbar packs have a tendency to move when you ride a bike, but this one won\'t. The main zippered compartment is large enough for an extra tube, a patch kit or a mini inflator.Osprey Seral 7 Lumbar Hydration Pack FeaturesAirScape backrest with contoured hipbelt provides maximum stability.Hydrapak Osprey Hydraulics ® 1.5L Lumbar Hydration BagMagnetic Valve Nozzle Attachment System on Hip Belt.Easy access zippered main compartment with internal tool organizer.Double zippered hipbelt pockets.Dimension: 20 X 33.0 X 15 CM