CamelBak loves acronyms with double meanings. So while your first impression when shopping or researching on the internet is to type in "Mule" (as in the offspring of a donkey and horse), you really need to type in "M.U.L.E." to get the maximum number of search results which stands for Medium-to-Ultra-Long Endeavors.
The M.U.L.E. has been redesigned and is now available in new colors. See below for more information and a side-by-side photo comparison.