Camelbak classic 20 litre hydration packthe quintessential bike hydration pack with the convenience of external fill via the quick release flap on the front of the pack holds the industry leading 2l antidote reservoir one small zip pocket on front holds keys and other essentials features antidote resovoir features 14 turn easy openclose cap lightweight fillport dryer arms center baffling and low profile design patented big bite valve hydroguard technology pureflow tube easy