The Viridian X5L Green Laser w. Tactical Light fits on virtually any firearm with a rail. It's compact design fits between the trigger guard and muzzle on a pistol, and with a remote pad it can fit comfortably on a rifle as well. It provides a green laser an light, both of which can strobe independently of each other. The light shines at 154 Lumens on constant and 187 on strobe.
If you're using a pistol, you can also get a Viridian TacLoc holster to use the X5L's ECR, or Enhanced Combat Readiness. With the ECR the X5L automatically shuts off when holstered and turns back on when drawn, so you can quickly sight in your shot without changing your grip whatsoever, no need to push any buttons! For more information on the X5L or TacLoc holster, visit the links above!