• 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). • Accurate collimation is essential for high power observing. Stars will become more like pin points of light, and Planetary / Lunar detail will be enhanced. • 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.