1.25" 99 Percent reflectivity Everbite mirror, 60 degree viewing

In addition, the diagonal uses Everbrite dielectric coatings on its first-surface mirror for an astonishing 99% reflectivity. In addition to higher reflectivity than a conventional aluminum or silver coated diagonal, the Everbrite coatings also provide higher contrast and resolution during critical observations of subtle low-contrast lunar and planetary details.

The mirror housing is precision-machined from a single block of solid aluminum, rather than simply a flimsy plastic housing or sheet metal stamping, as with lesser imported diagonals. A solid metal backplate over 4/10ths of an inch thick holds the mirror in perfect optical alignment. Both focuser and eyepiece barrels are antireflection threaded internally for higher contrast. The 1.25" barrel that fits into the focuser or visual back is also threaded to accept standard 1.25" filters. A groove cut into the outside of the barrel acts as a safety stop to keep the diagonal from falling should the scope's visual back or eyepiece holder thumbscrew loosen slightly from cold or use. The 1.25" eyepiece barrel uses a non-marring soft brass compression ring to hold eyepieces in place, rather than a thumbscrew that contacts the eyepiece barrel directly.

This is an absolutely premium 1.25" diagonal that will give you all the visual performance your scope is capable of delivering. It works with virtually any Schmidt-Cassegrain, Maksutov-Cassegrain, or refractor that uses a 1.25" star diagonal. It's a worthy and visible upgrade for the lunar, planetary, or terrestrial observer.