If you're the type that likes to trick out your carbine, then you might want to check out LaserLyte's K15 Kryptonyte sight, now in desert tan.
It mounts onto any modern rifle or carbine with three-inches of Picatinny or weaver type rail and is constructed of aircraft-grade 6061 aluminum.
The bright green dot makes target acquisition fast and efficient. The green laser can be seen in daylight up to 100 yards. At night the laser can be seen up to a mile away.
It provides 1.5 hours of continuous-on power on a single CR-123 battery. It also features a momentary-on setting that works with a 10-inch long tape switch that can be mounted on your weapon with provided Velcro strips.
It weighs 5.4 ounces and retails for $249.95. It's also available in black.