G-Sight BSG-338 .338 Lapua Mag Laser Bore SIGHT - Gold Plated - Button Activated, Gold Finish Class 3A laser &lt; 5mw, constant "on" laser for sighting in optics/sights 635 Nm wavelength Laser is activated when bolt carrier Group applies pressure to the back button/ not intended for dry Fire training Gold finished high quality brass Batteries included