The Viridian RFX45 is an enclosed-emitter reflex green dot for pistols. It uses a native ACRO footprint and includes an RMR adapter, so it mounts to both ACRO-cut and RMR-cut slides. The sealed emitter keeps debris and moisture off the lens. Features: 5 MOA green dot Enclosed-emitter design, sealed against debris Native ACRO footprint, includes RMR adapter Fully multi-coated glass, 24x15.5mm window 10 brightness settings (8 visible plus 2 night-vision) Instant-On activation with brightness memory 90 MOA windage and elevation adjustment CR2032 battery, up to 50,000+ hours runtime 6061 aluminum housing, IPX6 water resistance Weighs ~1.73 oz Confirm your slide is cut for the ACRO footprint, or use the included RMR adapter for RMR-cut slides.