I saw this on IG, and it looked like a better use of $100 buying a new trigger.

For those who aren't familiar with it, it presses against the trigger bar and when you pull the trigger it breaks with an audible click then resets the trigger bar.  

I find it works better with my mutant not - Glock than my G19. 4. The trigger safety seems to catch the frame slightly as you pull, resulting in a wierd crunch before the trigger "breaks".

Because it's not activating the sear and striker its not a perfect analog. But it can be adjusted either via the Allen head or a set of Alternately weighted springs and provides a good tactile response and ability to work the trigger.

I've never really got into dry fire because I've been relegated to resetting a striker or DA/SA trigger. But this seems like a really good way to conduct draws, fire multiple shots, and develop rhythm on the trigger while moving. It's also humbling to do this dry fire with a MRDS, you see lots of really bad habits you don't when shooting one slow dry shot on irons.

Mine had always fit. But I think the trigger blade catches through its movement