Molded glass aspheric lens with high-performance coatings for superior light transmittance and zero distortion; Can be direct mounted to any SIG pistol with the pro slide cut; Spring-loaded side battery tray released by a push button - no need to remove the optic to change the battery; Motion-activated illumination system powers up when it senses motion; Magnetac automatically turns the optic off when holstered in a compatible holster, and instantly turns the optic on when drawn from the holster; Designed, developed, tested and assembled in the USA