2" Mirror Diagonal with XLT2 SCT mirror diagonal with high performance XLT coatings 1 10th wave mirror is tested with an interferometer to ensure quality Housing is precision machined to achieve and hold good optical alignment Includes a 2 to 1. 25 adapter and aluminum carry case 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