Montane Water UltraFlask 500ml The Montane UltraFlask 500ml by Hydrapak is a compactable flask for quick, easy hydration when on the move. The flask compresses for easy storage and prevents water from sloshing. The new wider top opening allows for quick and easy filling/cleaning whilst the high-performance soft silicone bite valve provides a high flow rate. Soft, compactable and convenient, the Montane UltraFlask is the ideal water bottle companion for practicality and space-saving on your adventures. As you drink, the bottle shrinks, meaning that there is less water movement. As well as this it can be twisted or collapsed to a quarter of its size. This makes it easily storable in a fully packed bag, or even small enough to put in your pocket. Ultra-durable and abrasion-resistant, the bottle can be put through a lot whilst withstanding damage. As well as this, the 3D base provides added protection. The wide screw top opening allows you to easily refill. Lastly, the high