E7CD Telescope Collimation Eyepiece Lightweight 125-inch Telescope Collimation Eyepiece Accessory Replacement Durable _x000D_ Features: _x000D_ _x000D_ -Fits in 1.25" focusers and easy to use;simply cap the telescope, remove the diagonal, and place the eyepiece directly in the focuser. _x000D_ -For aligning optics of Newtonian reflectors, Dobsonian reflectors, and Schmidt-Cassegrain Telescopes (SCTs). _x000D_ -The short collimator for mirror (reflector) telescopes has a 45 degree plate for easier visual accuracy. _x000D_ -Item was made by aluminum with crossh at the bottom allow quick and precise centering of the optics. _x000D_ -This collimation eyepiece can be used for precisely collimating the Newtonian and Schmidt-Cassegrain reflector telescopes for better for image quality. _x000D_ _x000D_ Description:_x000D_ To get the most out of your Newtonian scope you really need to align or collimate the mirrors. It can take some for time getting used to aligning both the secondary and primary mirrors and this short collimator can make it much easier. The short collimator for mirror (reflector) telescopes has a 45 degree plate for easier visual accuracy. 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 for optimum for focus at the point from which the for image will be viewed (the eyepiece or possibly a camera)._x000D_ _x000D_ _x000D_ Specifications: _x000D_ _x000D_ Material: Aluminum Metal Structure_x000D_ Size: 32mm * 65mm / 1.25in * 2.56inch_x000D_ _x000D_ Package include:_x000D_ 1 * Collimating Eyepiece_x000D_ _x000D_ _x000D_