The KonusRex is nitrogen-filled and waterproof with silver mirror coating to improve light transmission. Phase-corrected, fully multi-coated lenses with BaK4 prisms further enhance the viewing experience with crisp, clear views even in low light conditions. The central focused KonusRex has an open-hinge construction with extra large eyepieces, and a long eye relief. This 10x42 model has a green rubber coating.