Thule made the Vital 6L Hydration Pack specifically for downhill mountain biking sessions. The stretchy back panel moves with you on the uphill as well as the down, and it's incredibly well-ventilated to keep you cool and comfortable. The Vital includes Thule's 2. 5L Hydrapak hydration reservoir with a clever ReTrakt hose that offers hands-free retractability as soon as you're drinking. The 6L compartment includes loops for tire pump and shock pump, an interior pocket to secure valuables, and enough space for a light layer and snacks. Thule positioned the side pockets so you can get a water bottle or energy bar with the pack on.