The folks at Double Alpha have done a splendid job on this product. It does everything that it is advertised to do. I purchased CZ magazines for my Shadow 2, and so far they are doing a wonderful job, which I will explain:
1. Their shape and feel closely follow those of a loaded 18 round magazine. Now I can do reloads with a more realistic magazine and gun weight, so that I'm not caught by surprise at the weight of a magazine during live fire. Magazine drops and insertions feel just the same as the real thing. My mag release is configured for a a left handed shooter and the practice magazine works just fine.
2. Real magazines are subjected to less wear as they are no longer subject to being dropped during dry fire. Another bonus is that there's no anxiety over the possibility of introducing live ammo to your dry fire routine.
3. The simulated followers do not cause the slide stop to stop the slide, which is a very welcome addition!
Very warmly recommended!

Un my Glocks, I use a G35Gen3 with G22Gen3 change system, they work perfectly.
They are held and reloading works.
Also in my G19Gen3, for concealed carrying, they work without problems.

Chris

Dry fire is hard work! No one likes doing it, but those who do - will surely better their skills set if they would spend 10-15min a day dry firing. I have used different magazines over the years for dry fire from dummy mags to the real deal while damaging them more often than not but slamming them repeatedly on the floor (ouch, that is expensive). Finally I came across the Double Alpha mags! Man, these are sweat!! The lock snugly into my CZ Shadow 2 and release like a charm. No brainer really.

The 3 mags fit perfectly in my G17 Gen3 with magwell.
Excellent mags for Reloading training with timer. Excellent products.
MT.