The Camelbak M.U.L.E. 12 Hydration Pack - 100oz is a hydration pack for mountain biking. When the distance increases in length, opt for the mid-size pack with the 100oz hydration reservoir included. There is plenty of space for the reservoir, while still leaving room for layers, snacks, tools, and a repair kit. The Crux 3L Reservoir is easy to fill and drink from, allowing you to continue pushing the limits up and down the mountain.