This adaptor barrel screws to the back of all popular SCTs (Meade and Celestron) and allows all standard 2" push-fit accessories to be attached to the SCT threaded back. New design has two nylon lock screws that help minimise the risk of sudden equipment rotation due to unscrewing of the adaptor. Two versions of the adaptor are available: AC307 standard length (41mm total length inc thread) for normal visual use, and AC478 Ultra Low-profile (31mm total length inc thread) for CCD camera and other photographic uses. Black anodic dye finish with two nickel-plated screws and two nylon screws.