"The Vortex Optics Viper HD 12x50 Binocular is designed for performance in low-light conditions. To make the most of the 50mm objectives, the lenses are made of High Density (HD) Extra-low Dispersion (ED) glass with a phase-corrected apochromatic optical system that produces images that are bright and crisp, with true color transmission across the entire field of view without distortion. All the optical surfaces are fully multicoated with Vortex's XR coatings. This anti-reflective coating ensures minimal light loss and maximum light transmission through the lenses. The roof prisms feature dielectric coatings with better than 99% reflectivity to make sure as much light as possible makes it to your eye. This binocular is designed to take the rigors of the outdoors. External surfaces of the lenses feature ArmorTek scratch-resistant coatings that not only resist abrasions, they also protect them from oils and dirt. The optical tubes are argon-filled and o-ring sealed to be water and fogproof. The Viper has a center focus wheel that is easily accessible with either hand, with a right-eye dioptric adjustment for crisp and sharp focusing. Twist-up eyecups let you customize your eye relief with or without eye wear. Rubber armoring on the body help ensure a non-slip grip, while providing protection against drops and impacts.|HD Lens Elements: HD (High Density) extra-low dispersion glass delivers impressive resolution and color fidelity, resulting in High Definition images|XR Fully Multi-Coated: Proprietary coatings increase light transmission with multiple anti-reflective coatings on all air-to-glass surfaces|Dielectric Prism Coatings: Multi-layer prism coatings provide bright, clear, color-accurate images|Phase Correction: Coating on roof prism models enhances resolution and contrast|Roof Prism: Valued for greater durability and a more compact size|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|ArmorTek: Ultra-hard, scratch-resistant coating protects exterior lenses from scratches, oil and dirt|Rubber Armor: Provides a secure, non-slip grip and durable external protection|Adjustable Eyecups: Twist up and down to precise, intermediate settings to maximize custom fit for comfortable viewing with or without eyeglasses|Center Focus Wheel: Adjusts the focus of both binocular barrels at the same time|Locking Diopter: Adjusts for differences in a user's eyes. Located on right eyepiece|Tripod Adaptable: Compatible with a tripod adapter, allowing use on a tripod or car window mount"