ARO (Advanced Rifle Optic) is an advancement on our popular 20mm 403 and 503 series optics. ARO features an all-new 22mm housing design that mates perfectly with our magnifier series, an all-new 1.63 lower 1/3 co-witness pedestal mount, and compatibility with a new lens cover and anti-reflection device system (available separately). The ARO series is available as a 2MOA dot only or with our Multi-Reticle System (MRS) in Red, Green, or Gold dot colors. Specifications for Holosun ARO Advanced Rifle Optic 1x22mm Reflex Red Dot Sight: Manufacturer: Holosun Color: Black Fabric/Material: Aluminum Magnification: 1 x Objective Lens Diameter: 22 mm Reticle: 2 MOA Dot Brightness Settings: 12 Eye Relief: Unlimited Adjustment Click Value: 0.5 MOA Battery Type: Lithium Metal, CR2032 Battery Life: 50000 hours Water Resistance Level: IP67 Weight: 3.38 oz Red Dot Sights-Footprint: Not Applicable Package Contents: Holosun ARO Advanced Rifle Optic 1x22mm Reflex Red Dot Sight