Introducing the New William Optics 2014 Dura-Bright diagonal - a dramatic step forward in the evolution of mirror diagonals!This 90° 2"mirror-type star diagonal has a Dura-Bright 12mm thick mirror, 1/10 or better wave surface accuracy, and dielectric mirror coatings for 99% reflectivity which provides higher contrast and resolution during critical planetary, lunar and binary star observations. Features a 2" nosepiece for insertion into refractor telescopes and other 2" focuser barrels.Dura-Bright features 100% real carbon fiber side plates that add that touch of class your scope deserves. It is William Optics' highest end mirror diagonal and designed for high-end scopes such as FLT-98, FLT-110 and FLT-132.The WO 2" Dura-Bright Diagonal was designed with several unique features to provide optimum performance and years of use.Top-Notch Performance and brightness Dielectric coating allows 99% reflectivity. High precision 12mm thick mirror substrate flat for optimal image stability. Polished to 1/10th wave or better accuracy. Accurate design guarantees constant alignment. No further alignment needed.Meticulous Craftsmanship 2" to 1.25" eyepiece adapter included. Lock screw for eyepiece/adapter. Big, knurled thumbscrews are easy to turn even with gloves on. Threaded for 48mm filters. Compression rings (both on diagonal and adapter) to prevent barrels from marring. Internal safety stop prevents 2" barrels from hitting the mirror.Strikingly Beautiful Patented, elegant design. High-quality machining out of the best aluminum. Internal anti-reflection baffling for highest contrast. Real Carbon Fiber side plates