Soft bottle that is compressible while you drink: once empty, it takes up less space in the backpack. The valve allows for quick and effortless hydration. It is made of TPU (thermoplastic polyurethane), PVC-free, phthalate-free and bisphenol A-free. TPU has no taste and does not change the taste of the contents. Soft flasks have the advantage of not having hard surfaces in contact with the body and allow you to see the quantity of liquid remaining due to their transparency. They also comply with European and American (US FDA) standards relating to food containers. Their use is perfect for trail running, mountain running and all outdoor activities in summer and winter.