It does not contain instructions for use, so you have to discover on your own how to seal and how to open the spout. Otherwise, it does its job just fine

The satisfaction I have from this specific flask cannot be described. Firstly, I consider it a necessary tool for hikers. I imagine it serves equally well for other hobbies, but I don't have an opinion on that.
Very practical construction and easy to clean. Its mouthpiece works with the classic bite and it even has a protective cap. It is designed to be placed correctly in the back position of the backpack. There, I dare to say, although it is not a thermos, the water remains cool. If it is put in a thermos, then the user achieves the desired temperature.
Beautiful and elegant construction.

I recommend washing it before the first use, to remove any industrial residue and plastic smell. It performs perfectly during a 6-hour climb.

The product already comes with the upgraded helix nozzle valve, which costs an additional 15€ to purchase. Due to the intermediate membrane, the bag maintains a low profile, making it ideal for the back. So, for the excellent quality and relatively low price, I am fully satisfied.