Green laser aiming devices are becoming smaller, cheaper and more common.  The latest introduction comes from LaserMax with a green version of the CenterFire for the Ruger LC9 and LC380 pistols.

The CenterMax aiming devices fit on the frame of the gun, forward of the trigger guard and under the barrel.

The unit weighs about one ounce and runs on a single 1/3 N lithium battery.  According to LaserMax, the battery will run the unit for more than five hours continuously.  The CenterFire carries a MSRP of $249 and a battery is included.