The Vortex Razor HD Binoculars feature premium HD (High Density) extra-low dispersion glass delivers the ultimate in resolution and colour fidelity, resulting in High Definition images. Premium proprietary coatings deliver the highest level of light transmission with multiple anti-reflective coatings on all air-to-glass surfaces for maximum brightness. O-ring seals prevent moisture, dust and debris from penetrating the riflescope for reliable performance in all environments, while argon gas purging prevents internal fogging over a wide range of temperatures.