For a more secure attachment of your camera to a Schmidt-Cassegrain telescope (or any scope using typical SCT threads) replace your nosepiece with this adapter. One end screws into the female t-threads on the front of the camera or filter wheel, and the other end screws onto the rear cell threads typically found on most commercial Schmidt-Cassegrain telescopes. A matching hard plastic dust cap screws over the t-thread end if the camera is removed for any period of time.