These days hydration packs are not only worn by highly active users, they are used by many people at work and for leisure. They are a simple and convenient way to have water on hand while you are on the move. Ideal for walking, running, cycling, on your surf ski or almost any outdoor activity or work that requires both hands free! The Blue Tongue Range includes a 2L hydration reservoir, and is designed to fit a second reservoir plus still have plenty of storage capacity.