I waited a bit before making the comments, just to realize that this was effective. Three weeks after installation, it seems to work. The shower water is less aggressive, for sure. Is this going to last as long announced, while there, we'll see. For the price, it is hoped that it will last the given time. But it is true that there is a notable difference, right from the first use.
Quick and easy installation, as long as you check the space between the arrival of the mixer and the wall (it takes at least 6 cm to be quiet).