That’s one way to limit capacity.
These mags are much better than the KCI crap.
I have a couple buddies who use ETS magazines in their Glock 17 and 19s as well as AR9 rifles in local combat pistol/rifle matches as well as a 3gun match...haven't seen any issues yet. And the mags have hit the ground many times during reloads and stepped on with no damage. I don't own any but have tried there's a few times. I prefer factory Glock mags, although its nice to be able to see at a quick glance how many rounds are in them as opposed to looking at the witness holes(or none at all in PMags). I do use PMags for range and matches, but factory Glock mags is what is used for home protection and business.
I had a KCI literally explode during a steel challenge match and some of mine won’t lock the slide back anymore.