Quality open compact red dot Burris Fast Fire II. This product is certified for shocks of high performance calibers or for mount on pistols. A light sensor automatically adjusts the brightness of the aiming point according to the intensity of the ambient environment. It has a very long battery life (depending on usage up to 5 years). Attaching the red dot is automatically switched off and "ON" to conserve battery life. Mounting Picatinny/Weaver makes use of any weapon with fixed bases. Red dot is waterproof, uses a CR2023 battery.