I don't know which one I have, however the bladder can take more than 2L of fluid. I just fill it with cold water and away I go. As I have a significant scar on my upper right back, I was resistant to wearing any type of back pack-however, the camelbak has a sliding set of clasps at the top-so-when I hitch it together, there is NO pressure on my old scar nor over the muscles. The water stays reasonably cold for a long time. There is padding on the back, too, that allows a barrier between my skin and shirt, to leave room for sweat dispersion and evapoartion. I love the little pockets--that let me carry keys, ID--small towel, binoculars--kleenex and all that jazz. I am Very pleased with the whole device. I have no problem getting the mouth piece to my mouth. All in all, this is a piece of gear I wouldn't be without anymore.