Spend a day in the mountains trail running or mountain biking with Jack Wolfskin's Speed Liner Hydration Backpack carrying the essentials. An ACS Tight Lite suspension system gives this daypack a close fitting design that still allows active ventilation and optimum freedom of movement. Waterproof Flex Shield works with durable yet lightweight Cross Rip fabric to ensure protection and comfort. The Speed Liner also features a hydration sleeve with a tube duct and attachment for your own reservoir. Stretchy straps accommodate most helmets, and the rain cover pulls out of the base compartment when wet weather threatens your gear. There are reflectors and an anchor for your own flashing light, too.