Easy to see and its very accurate - Streamlight TLR-2G LED Rail-Mounted Tactical Light

I put this on a Glock 17 and it works extremely well indoors in lower light conditions. The green laser is easy to see and it's a very accurate combination in low light. It didn't take long to zero the laser at 12 yards but because there is no indexing (clicks) on the adjustments you can't really get a perfect zero without great patience and lots of ammo. Good enough isn't too hard to achieve.

I tried the green laser outdoors on some steel plates and was disappointed. I could see the green dot on the plates but only if I stared for a while. The front fiber optic sight was far better than the green laser even in cloudy conditions. Still, I like the options. The light, the laser or the fiber optic front sight should work in pretty much every condition.