Athlon Optics 4-20x50 Argos HMR BDC 600A SFP IR MOA, 1" Tube 4-20x magnification 50mm objective lens 1" tube diameter Capped turrets 3.6" eye relief 10 yds to infinity side parallax adjustment 27.9-5.6 feet field of view at 100 yards 0.25 MOA click value 15 MOA adjustment range per rotation 80 MOA total elevation and windage adjustment 13.2" long 21 oz BDC 600A SFP (Second Focal Plane) MOA Etched Glass Reticle Illuminated reticle with variable brightness Advanced Fully-Multicoated lenses Aircraft grade aluminum One piece tube Waterproof Fogproof Shockproof Argon purged Lifetime warranty