I own three of these - Crimson Trace Rail Master Universal Fit Green Laser Sight

I have three of these, one on my Glock 19, one on my Ruger 22 pistol, and I just bought one for my Windham AR 9mm. I mounted the Crimson Trace Rail Master under the front of my 1x-4x scope, and it fits perfect there, protecting it, and easy to find to turn on with my thumb. I really like the Crimson Trace Rail Master on my AR because it's constant on, instead of just temporary where I have to constantly hold down a switch. With my Steiner scope I have three ways to sight, crosshairs, red dot, and green laser with the Crimson Trace. No need for iron sights, because the crosshairs are my backup for dead batteries. My eyes are too old for iron sights anyway, and with the Crimson Trace green laser, I can shoot from the hip if need be, which I couldn't do without a constant on switch.