Ok, so I got this and played with it a bit. Seems sturdy, definitely bright. Once I put it on a gun, Taurus PT-99, I found that the light will flash on for a fraction of a second when the slide is racked. It probably happens when shooting also. I was able to easily adjust the clamp to allow proper tension, not sure why people have said that the clamp does not adjust. I believe this light is defective and I'll try to follow up on getting it replaced, but I've sat on it for awhile now so I think I own it. Overall I'm willing to say it's a good product.
Pros: easily installed
Cons: Light malfunctions
This review was written in the old system and had content requirements that are different than reviews written today.