The light, flexible 500 ml Flask is your practical accessory to always stay well hydrated on a trail run or when mountaineering. You must always drink enough to be able to give your all on the mountain. With the 500 ml Soft Flask, you always have fluids quickly accessible and can immediately quench your thirst with the practical bite valve. The soft flask is made of durable BPA- and PVC-free materials and can be quickly filled and easily cleaned with its wide mouth. The valve closes automatically after every drink to prevent annoying dripping. The flask’s volume shrinks on its own when you drink to hinder that annoying swooshing of fluids back and forth. The front pockets of this DYNAFIT running vest have been made to match the shape of a flask so they stay put and are stable while running.