The short collimator for mirror (reflector) telescopes has a 45 degree plate for easier visual accuracy. This collimation eyepiece can be used for precisely collimating and Schmidt-Cassegrain reflector telescopes for better images quality. Features - Color: Black. - Size: 7.00X4.00X4.00cm/2.75X1.57X1.57 inch. - Material: Aluminum alloy. - To get the of your scope for telescope you really need to aligns or the mirrors. - Short collimator it much easier. The collimator for mirror (reflector) telescopes. - Collimation is the alignment of elements inside an optical system like a telescope. - Colimating a telescope consists of adjusting the tilt and position of the mirrors and lenses to ensure that the focal point reaches optimum focus from which the images will be viewed (the eyepiece or possibly a camera). - Adopts precision production to improve the stable characteristics and high reliability. Package list: 1 x Collimating Eyepiece