There are few telescope accessories that work as hard or matter as much as a diagonal! An integral part of the optical chain, a good diagonal can make a big difference in the quality of the image you see. A 2” diagonal is required if you want to use 2” eyepieces when observing with your telescope. The larger 2” barrel allows you to see a bigger percentage of the telescope’s light cone, which works wonders for capturing faint deep sky objects with low surface brightness.\n\nThe Celestron 2” Mirror Diagonal was built for superior performance. The housing is machined with precision instruments to make sure the optics stay perfectly aligned. The diagonal’s mirror is tested with an interferometer, and is guaranteed to be 1/10 wave or better. The mirror’s surface is covered with the same high performance XLT coatings used on Celestron’s best telescopes, and the result is a sharp, bright image that will satisfy the most discriminating amateur astronomer.\n\nThis 2” diagonal threads securely to the rear cell of standard Schmidt-Cassegrain telescopes. To take advantage of the XLT Diagonal’s extra light throughput, insert a 2” eyepiece into the barrel. If you want to use 1.25” eyepieces, slide the included 2” to 1.25” adapter into the eyepiece barrel and secure it with the thumbscrew. When you’re not observing, store your diagonal in the included aluminum case for protection.\n\n- 2” SCT mirror diagonal with high performance XLT coatings\n- 1/10th wave mirror is tested with an interferometer to ensure quality\n- Housing is precision machined to achieve and hold good optical alignment\n- Includes a 2” to 1.25” adapter and aluminum carry case