2" Zenith Diagonal Dielectric Mirror for Refractor Astronomical Telescope 99% Reflection Accessories 90 DegreeMulti layered enhanced dielectric coatings that produce 99 percent reflectivity for brighter, sharper images. 2 inches nosepiece fits 2 inches telescopes; accepts standard 2 Inch filters; eyepieces; Barlow lenses and other accessories,a 2 inch to 1. 25 inch adapter incuding,you can also use 1. 25 accessories Diagonal provides a comfortable 90 degree viewing orientation when observing the night sky through a refractor telescope Brass compression ring;