A sighting system as mission adaptable as you are. The Bushnell AR Optics 3-9x 40mm Bullet Drop Compensating (BDC) Reticle riflescope with side parallax focus features target turrets for pinpoint-precise adjustments, plus caliber-specific reticle to deliver every round with peerless accuracy. Drop Zone-223 BDC reticle is calibrated for 55-62 grain, 223 REM/5.556 loads. Zeroes at 100 yards, with aiming points out to 500 yards. Fully multi-coated optics for incredible brightness, and fast focus eyepiece deliver maximum accuracy and reliability. Nitrogen purged to remove any vestige of internal moisture, and O-ring sealed to prevent the entry of dust or moisture. Made of high-durability aluminum alloy, anodize-finished and sealed to protect the inside from elements. Riflescope is rustproof, virtually scratchproof and a beautiful complement to even the most expensive AR platform firearm.