The O-Ring Tactical Training Laser Cartridge utilizes technology that provides immediate feedback with every pull of the trigger. Our dry fire laser ammo cartridge fits precisely in the chamber of your gun. With every pull of the trigger a firing-pin activated switch, allows the laser to indicate the impact of the bullet with a bright red dot. A rubber snap cap at the rear of the cartridge protects the firearm under a “dry fire” situation. SEE OUR VIDEO This allows you to train with your own personal firearm, Practice in the comfort of your own home and Eliminates the need for costly practice ammunition. Excellent for classroom training or repetitive practice drills. Dry fire laser ammo specifically designed to fit .40 S&W hand guns.