This smaller, slimmer improvement upon the ATIK OAG is an easy to use, high quality off-axis guider that works splendidly with the ATIK One CCD Camera, especially when used with Atik's GP Guide Camera (Sold Separately). The two components work perfectly together and easily attach to a telescope on one side, and your ATIK One on the other! You just need a tge 2 inch adapter or a T-thread accessory to attach the OAG to your Telescope, and you'll be ready to go! The pickup prism inside the OAG diverts some of the light coming through your telescope towards the guide camera, and can be adjusted to compensate for the differences between various telescopes relatively freely. As for the OAG itself, it boasts an extremely smooth focusing system that is both fast and simple to adjust; all you need to do is turn the focusing ring clockwise to move the camera support down, or counter-clockwise to move it up. There is a full 5 mm of travel. Note: Images show the Atik One OAG mounted on an Atik One camera, and an Atik GP guide camera mounted on the OAG. Both cameras are sold separately.