The Burris FastFire C is an open-emitter micro reflex red dot on the RMSc footprint, sized for sub-compact and micro-compact carry pistols. It runs an "Always On" 6 MOA red dot with automatic brightness so it is ready when you draw. Features: Open-emitter micro reflex red dot 6 MOA red dot RMSc footprint for sub/micro-compact carry pistols CR2032 battery, bottom-loading, ~25,000-hour "Always On" runtime Automatic brightness adjustment Anodized aluminum housing, under 1 oz Burris part #300239 RMSc footprint fits a wide range of carry pistols. Verify your slide is cut for the RMSc footprint before ordering.