This high quality 90-degree multicoated mirror diagonal for refractors allows you to take advantage of the wider field of view provided by 2" eyepieces. This Skywatcher 90 degree star diagonal is suitable for telescopes which use 2 inch (50.8mm) eyepieces, plus also comes with a 1.25 inch adapter. A star diagonal is designed to make viewing more comfortable when the telescope is pointed at high angles. Suitable for use with refractor and catadioptric telescopes.