With long eye relief, a fast-focus eyepiece, fully multi-coated lenses and resettable MOA turrets, there s no compromising on the Crossfire II 4-16x50mm AO Dead-Hold BDC Riflescope . Clear, tough and bright, this riflescope hands other value-priced riflescopes their hat. The hard anodized single-piece aircraft-grade aluminum tube is nitrogen purged and o-ring sealed for waterproof/fogproof performance. 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. Tube Size: 30 mm diameter. Single-Piece Tube: Maximizes alignment for improved accuracy and optimum visual performance, as well as ensures strength and waterproofness. Aircraft-Grade Aluminum: Constructed from a solid block of aircraft-grade aluminum for strength and rigidity. Waterproof: O-ring seals prevent moisture, dust and debris from penetrating the riflescope for reliable performance in all environments. Fogproof: Nitrogen gas purging prevents internal fogging over a wide range of temperatures. Shockproof: Rugged construction withstands recoil and impact. Hard Anodized Finish: Highly durable low-glare matte finish helps camouflage the shooter s position. Capped Reset Turrets: Allow re-indexing of the turret to zero after sighting in the riflescope. Caps provide external protection for turret. Adjustable Objective: Adjustment for riflescope s objective lens provides image focus and parallax removal. Fast Focus Eyepiece: Allows quick and easy reticle focusing. Product Specifications Magnification: 4-16 x Objective Lens Diameter: 50 mm Eye Relief: 3.7 inches Field of View: 25.3-7 feet/100 yards Tube Size: 30 mm Turret Style: Capped Adjustment Graduation: 1/4 MOA Travel per Rotation: 15 MOA Max Elevation Adjustment: 50 MOA Max Windage Adjustment: 50 MOA Parallax Setting: 25 yards to infinity Length: 14.2 inches Weight: 23.6 ounces