Vortex Diamondback 4-12x40 Riflescope Dead-Hold BDC (MOA). Ideal for big game, predator/varmint, muzzleloader, slug shotgun, and long range applications. Dead-Hold BDC reticle has a customized design that helps eliminate guesswork on hold-over and windage corrections. Good for any hunting or shooting at varying ranges where estimating hold-over would be a concern. SPECS: Magnification: 4-12x. Objective Lens Diameter: 40mm. Eye Relief: 3.1 Inches. Field of View: 32.4-11.3 feet/100 yards. Tube Size: 1 Inch. Turret Style: Capped. Adjustment Graduation: 1/4 MOA. Travel per Rotation: 15 MOA. Max Elevation Adjustment: 60 MOA. Max Windage Adjustment: 60 MOA. Parallax Setting: 100 Yards. Length: 12 Inches. Weight: 14.6 Ounces. OPTICAL FEATURES: Fully Multi-Coated: Increases light transmission with multiple anti-reflective coatings on all air-to-glass surfaces. Second Focal Plane Reticle: Scale of reticle maintains the same ideally-sized appearance. Listed reticle subtensions used for estimating range, holdover and wind drift correction are accurate at the highest magnification. CONSTRUCTION FEATURES: Tube Size: 1-inch diameter. Single-Piece Tube: Maximizes alignment for improved accuracy and optimum visual performance, as well as ensures strength and waterproofness. Waterproof: O-ring seals prevent moisture, dust and debris from penetrating the riflescope for reliable performance in all environments. Fogproof: Argon gas purging prevents internal fogging over a wide range of temperatures. Shockproof: Rugged construction withstands recoil and impact. Precision-Glide Erector System: Uses premium components in the zoom lens mechanism to ensure smooth magnification changes under the harshest conditions. Capped Reset Turrets: Allow re-indexing of the turret to zero after sighting in the riflescope. Caps provide external protection for turret.