Astromania 1.25Inch Metal Collimating Cheshire Eyepiece without Laser for Newtonian Reflector Telescope - Short Version Fits in 1.25" focusers and easy to use;simply cap the telescope, remove the diagonal, and place the eyepiece directly in the focuser. For aligning optics of Newtonian reflectors, Dobsonian reflectors, and Schmidt-Cassegrain Telescopes (SCTs). The short collimator for mirror (reflector) telescopes has a 45 degree plate for easier visual accuracy. Item was made by aluminum with crosshair at the bottom allow quick and precise centering of the optics. This collimation eyepiece can be used for precisely collimating the Newtonian and Schmidt-Cassegrain reflector telescopes for better image quality.