No more leaking bottles! Eliminate accidental leaks with the 500ml Ultra Flask featuring an auto-sealing high flow phaser bite valve and a twist-locking cap which shuts off all flow to the valve, allowing you to stash it in your waist pack without the worry of annoying leaks. A large 42mm cap entry ensures quick and easily refilling at race aid stations, while the soft and flexible design ensures it shrinks down as you drink, reducing water movement as you run and conforming to any pocket shape. Constructed from highly durable, abrasion resistant TPU - the bottle is easy to clean and can be filled with both hot and cold liquids. The 0.5L Ultra Flask is the ultimate running soft flask – flexible, durable and leak-proof!