The Celestron T-Ring for Sony E-Mount Cameras allows you to use an E-mount camera to capture photos with your Celestron telescope. The T-ring attaches to the lens mount of your camera, securing via a sturdy bayonet flange that locks in place just like a lens. Then you can attach the other side of the T-ring to your telescope. A Celestron adapter (sold separately), such as the Celestron T-adapter, will be required to do this. It's the optional adapter that will secure to your telescope, and the T-ring will then thread onto the adapter. The Celestron adapter you choose depends on the type of photography you wish to do.