The absolute top of the line among Konus binoculars the Konusrex series features the incomparable resolution and brilliance of the Silver Mirror Coating treatment thus achieving a light transmission as high as 96 percent.The outstanding optical performance of these binoculars is further enhanced by the fully multi-coated lenses with Phase Correction and professional BAK-4 prisms. Phase Corrected Open Hinge Construction Bak-4 Prims Fully Multi-coated Optics Nitrogen Filled Large Eyepieces Long Eye relief Waterproof Rubber Covered Central Focus Silver Mirror Coating Super Light Weight Extra Large Eyepieces