The Sightmark A-Spec M3 Reflex Sight is manufactured to be compatible for uses with a Shield RMS-C footprint, and it boasts a red auto-brightness control reticle to accommodate shooting at any time, day or night. The Mini Shot A-Spec M3 optic is perfect for subcompact guns, and is notoriously durable, aluminum alloy housing, IP55 water-resistant, shockproof, able to withstand up to .375 H&H caliber and operate in temperatures from -22F to 122F. With a battery life up to 100,000 hours and an included rubber cover, low-profile fixed mount and manual. FeaturesFits pistols with Shield RMS-C footprintAuto-brightness control reticleCowitness with standard pistol sightsRed reticle illuminationLightweight compact aluminum alloy housingRugged aluminum alloy housingIP55 water-resistantShockproofBattery life up to 100,000 hours