Nikon is proud to present Nikon 8x42mm EDG Waterproof / Fogproof ED Binoculars Edge 7561, a binocular for those whose adventurous spirit and dedication to success demands performance above all else. The most dynamic and advanced binoculars in the company's history, EDG (pronounced "edge") was engineered using Nikon 's latest cutting edge technology, but refined by nearly a century of glass-making heritage. Nikon's EDG binoculars optical system incorporates phase-correction coated roof prisms to enhance resolution, as well as dielectric coated sub-prisms to maximize light transmission. Interacting with fully multicoated lenses and ED glass, the high-grade prisms deliver extremely bright, clear, vivid images across the periphery of the viewing field. To further enhance viewing pleasure, these hunting binoculars have a thoughtful and convenient dual-phase central focusing knob provides both precise focusing and diopter adjustments in the Edge 8 x 42 binocular. This single, multifunction control locks the focus when diopter correction is necessary for unparalleled speed and convenience, yet discreetly integrates it within the central focus knob itself for understated style. As some hunters prefer using ergonomically contoured horn-shaped eyecups to block out peripheral light from the eyepieces these Nikon binoculars have them included them in a quick detachable style with each Nikon Edg binocular to accommodate both points of view.