I purchased a LaserLyte LT-9 laser training cartridge.
As I do a lot of dry fire, I figured a training modifier would make sense, especially as an addition to an optic on the pistol.
The laser is bright red, just like the dot of an RMR or an Aimpoint T1, so a hold over absolutely required in order to make this work, unless you want to run the red dot at lowest setting.
The rear of the LaserLyte is a rubbery push button. Essentially it is a small laser pointer then has a temporary on when the striker hits the rubber button.
As you can see the LaserLyte is slightly longer than a standard 9mm. The only issue I have found is that each barrel, especially aftermarket barrels, have slight variances in specifications. This causes the red dot to hit slightly off zero. So far I have seen this happen in the S3F barrel, but the Barsto and Gemtech barrels seem to be pretty dead on. I do not know if this is a rubber gasket issue, or overall size.
The other non-issue is that you have to stick something down the barrel to push it out as it will not eject out. That is not really an issue just something to consider.
Overall, having run it for a few weeks now, I have determined that it is definitely worth getting. A few considerations - once the LaserLyte is in the gun, it is as "safe" as it gets as it cannot be ejected without manual extraction and that means you can run it as such from concealment/etc. You have to rack the slide each time on a Glock, but can run double action if you have that type of pistol, it works well in this regard, giving you proper reps of immediate action.
The LaserLyte comes with some batteries but they are junk and/or old. I ended up buying it from Amazon, so I purchase a set of Energizer 377/376 battery pack. Though I have not had to change any batteries yet, I doubt I will go through them in a year or two.
My recommendation is that if you want to slightly modify your dry fire and training, then this is a good tool. Especially for dry fire dot torture or fast aiming from the draw. You can really start to dial down the little details if your shooting.