Holosun ARO Advanced Rifle Optic 1x22mm Reflex Red Dot Sight Red 2MOA Dot Reticle w/ HM3X Magnifier Black ARO-RD2 & HM3X. 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...