For the best images from your reflecting telescope, the optics need to be in precise alignment (also known as collimation). The Orion Collimating Eyepiece is an economical and accurate way to ensure perfect Newtonian mirror alignment every time.
After dealing with the frustrations of using a cheap laser collimator on my 12" Dob, I decided to explore a different method and thus bought this combo collimator. Once I learned how it worked it is very easy to use and is versatile in that with a small LED flashlight, it can be used in total darkness. Extremely accurate I highly recommend it