I have installed two doors, I have them for about a year, they are very stable despite the efforts of the little hooligan to violate / demolish them, in one I have installed two extensions (+28, +14) and in the other door one extension (+7). I have placed them with clamps just in front of the balcony doors and 10-15 centimeters above the floor, without the need to make holes in the walls and they are very stable and sturdy, they close by themselves and from both sides or you can adjust them to open/close only from one side, the only flaw I have encountered is that in the one door that is used very frequently, sometimes the lock gets stuck and does not unlock easily, it requires a little more force.

Easy installation, impressively stable without the need for a hole in the wall.
I got it along with the 28cm extension and it fit perfectly.
The auto close feature is fantastic, prefer it over the easy close, especially if you constantly pass through this door (e.g. staircase in a maisonette).

If set up correctly, it is the best on the market and very good value for money!
The first time we didn't set it up properly, but the second time it stood perfectly. Very good and with the bases against the wall very stable for a relatively calm child.