
I love the fact that fanny packs have caught on in the MTB world....I have been rocking them since they were first introduced and keep full-on hydration backpacks only for really really long days.
I take the 2L Dakine for any rides under 2 hours. Along with a externally mounted waterbottle, there is enough room to carry a small pump, spare tube, small tools and tire levers, plus my car keys and small cell-phone (larger phones like Galaxy Note or largest iPhone might be a tight fit with everything else already listed).
As with most Dakine products, quality is good and functions well.