We have to remember this is a 25$ laser site so it’s not fair to compare it to higher priced equipment.
It is super easy to install and even easier to zero in the aim. I have mine set for 50 feet giving me a couple inches high or low in the house depending on distance. I’ve shot 2 boxes of full metal jacket 9mm with it mounted to my Glock 19. Aim stayed exactly where I set it on round one!
The only issue I have with it is the on/off mechanism is a push button on the back of the unit. I have smallish hands so reaching the on/off mechanism has to be done with my off hand. If I move it back where I could reach it, I can’t get my finger between it and the trigger guard…
Over all, and for the price, it’s hard to beat so far!