The  Sky-Watcher 2″ 90° Dielectric Star Diagonal is a high performance diagonal for high-end telescopes. The high reflectivity of the mirror (99%) offer a bright image without losing luminosity. The high optical correction of the mirror (1/10 lambda) does not compromise the resolution or the contrast of the image. The CNC body of the diagonal is both solid and elegant, the telescope side  connection in threaded for 2″ filters while the eyepiece side has a brass compression ring for not damaging the barrels of the eyepieces. The diagonal includes a 2″ to 1.25″ adapter also equipped with brass compression ring. This accessory can be used only on telescopes equipped with a 2″ focuser.