Extra-low dispersion glass gives you an image with little or no chromatic fringes so the end result brings a clearer, sharper image XPL coating gives you extra protection against dirt, oil and scratches Advanced fully multi-coated lenses bring you better light transmission to bring optimal brightness and true color Argon purging uses the inertia gas with larger sized molecules to purge any moisture out of the tube, giving you better sealing and thermal stability