HD Optical System provides outstanding color fidelity, edge-to-edge sharpness and light transmission; XR Fully multi-coatings increase light transmission with multiple anti-reflective coatings on all air-to-glass surfaces; APO System corrects color across the entire visual spectrum; Optically Indexed Lenses optimize image sharpness and brightness from edge to edge; First Focal Plane Reticle - scale of reticle remains in proportion to the zoomed image. Constant subtensions allow accurate holdover and ranging at all magnifications; Daylight bright, illuminated reticle aids in faster target acquistion in bright daylight conditions; ArmorTek - Ultra-hard, scratch-resistant coating protects exterior lenses from scratches, oil and dirt; 34 mm diameter provides maximized internal adjustment and strength; Aircraft-Grade Aluminum Construction for strength and rigidity; Hard Anodized Stealth Shadow Finish