This is a good light/laser combo with nice switching. Only issue is that it was fab'd to be a little loose on the rail. I'm sure this was to accomodate minor differences in rail widths. I put the mounting side of unit in a vise (use rubber to protect from scratching) and slowly tightened until mount width decreased enough to fit tight on the rail. Do not over tighten or you won't get it on the rail by hand. Once the spring lock clicks where you want it on the rail, you will be able to zero in the laser and not worry about it moving anymore.
Pros: cheap, solid, bright
Cons: loose mount
This review was written in the old system and had content requirements that are different than reviews written today.