Many observers prefer to use a good-quality mirror diagonal instead of a prism diagonal with high-end telescope systems. The mirror in this 2" Orion Refractor Mirror Diagonal is meticulously polished to yield maximum performance. Housing is made of black-anodized aluminum. Barrel is internally blackened. This 2" diagonal accepts both 2" and 1.25" eyepieces (with included adapter). The 2" eyepiece holder has two locking setscrews for maximum eyepiece security. This telescope diagonal renders images that are right-side up and reversed left to right (therefore, not recommended for terrestrial observing).
Diagonals are not suitable for use with Newtonian reflector telescopes due to insufficient focus travel.