Athlon Optics , Cronus , Binocular , 8.5 x 42 ED Roof , E2ES System - E2ES System is a field flattening system that produces sharper, clearer images all the way from one lens edge to the other 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 - 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