Nikko Stirling Mountmaster IR series has been developed to provide a fast correction to focus and parallax through the adjustable objective (AO IR) lenses. Now you can adjust right down to targets that are only 10 yards if required! Featuring a 1 inch matte black alloy body tube, 1/4" MOA adjustments, 3/8" quick detachable mounts (included), waterproof, shockproof and fog proof.