HOLOSUN ARO-MRS ENCLOSED 2 MOA DOT/65 MOA CIRCLE RIFLE SIGHT ARO (Advanced Rifle Optic) is an advancement on their popular 20mm 403 and 503 series optics. ARO features an all-new 22mm housing design that mates perfectly with our magnifier series and an all-new 1.63" lower 1/3 co-witness pedestal mount. ARO is available as a 2MOA dot only or with their Multi-Reticle System (MRS) in Red, Green, or Gold. FEATURES: Shake Awake(TM) Shake Awake Technology is a standard feature on all current model Holosun optics and serves to extend battery life by deactivating the optic's LED while not in use. A highly sensitive motion sensor works to detect motion keeping the Mfg: Holosun