Ensure maximum light transmission without loss of optical quality with the Celestron Dielectric Star Diagonal, 1.25? with Twist-Lock. Upgrade your existing star diagonal to this premium one and enjoy brighter, sharper images without replacing your telescope. This star diagonal reflects the telescope?s light path 90° to provide a more comfortable viewing angle. In addition, the glass has 58 layers of dielectric coatings, which provide an over 99% reflective surface, delivering the maximum amount of light to the eyepiece. The twist-lock eyepiece holder secures any 1.25? eyepieces while keeping them centered in the diagonal, thus providing best opto-mechanical alignment between the telescope and eyepiece. Unlike traditional thumb screws, the twist-lock cannot scratch or engrave the barrel of your eyepieces. The twist-lock has an integrated 1.25? barrel stop that prevents 1.25? accessories with long barrels from damaging the mirror. All the diagonal?s mechanical parts are made of machined black anodized aluminum, except the twist lock rings, which are orange anodized for visibility. The interior of the barrel is glare threaded and painted flat black to prevent glare. With all its features and these high-end finishes, the Celestron Dielectric Star Diagonal, 1.25? with Twist-Lock is one of the highest quality 1.25" star diagonals that Celestron has ever offered.