Athlon Optics , Midas, Binocular, 10 x 42 ED Roof, ED Glass - ED glass gives you an image with little or no chromatic fringe so the final result brings a clearer and sharper image to your eyes ESP Dielectric Coating is a multi layer prism coating that reflects over 99% of the light to your eyes bringing you a clear, bright image that displays accurate color reproduction. Advanced FMC - Advanced Fully Multi-Coated lenses gives you better light transmission to bring optimum brightness and true color across the entire light spectrum. Argon Purged - Argon purging gives you better waterproofing and thermal stability Phase corrected prisms produce images that have better contrast, a higher resolution and better color reproduction