Requires at least 1 3/4" of rail space Advanced mounting technology provides the perfect fit; Minimum 1.75-inch of rail space Laser comes in vivid red or daytime green; Mint Green Light emitting diode adjustable from 120-4 Lumens Over-sized electronic touch pads ensure effortless activation for both left and right handed shooters Fully adjustable for windage and elevation, ensuring the most precise targeting over all shooting distances Auto-off after 10 min preserves battery power; AAA Battery Powered Class IIIA laser, &lt;5mW power output