First off, a quick rebuttal to a previous review. For laser only operation, one simply twists the light clockwise (as weapon is pointed down range) like a typical flashlight, maybe a quarter of a turn. The gasket is thick enough that it should still be sealed.
Super light, doesn't pull the gun down at all.
After initial zero per the instructions (25 meters) you won't be able to see the dot inside of 12 feet or so if you're looking straight down the sights. Then you have to go out and do some groups at different distances and see what's going to work for you. They do provide two Allen wrenches in a ziplock baggie and a CR2 battery. Mighty nice of them.
Pros: Light weight
Cons: Battery life
This review was written in the old system and had content requirements that are different than reviews written today.