The A-Spec M3 is manufactured to be compatible for uses with a Shield RMS-C footprint, and it boasts a 3 MOA red do which is auto-brightness controlled to accommodate shooting at any time, day or night. This 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, the A-Spec M3 is guaranteed to help you Make Your Mark.