Drinking bags are designed primarily for cyclists and runners during endurance races, but they are appreciated by anyone who likes to save space in their backpack or time during races. Compared to a traditional cycling bottle, a drink in a drinking bag stays cold longer, and its use is safer, faster and undoubtedly more convenient. The hydrovac consists of a water reservoir and a hose that easily attaches to the shoulder strap of your pack. We recommend using it with lightweight backpacks designed for running and cycling.