These quality cast-aluminium rings are custom made for use with all Sky-Watcher equatorial mounts & the AZ3 mount. The felt-lined hinge opens to allow easy installation of the optical tube & the locks can be loosened during use to allow tube Rotation & balancing. In order for astrophotography lovers to capture the spectacular views of the sky, these tube rings feature a standard tripod adapter (¼"") on one of the rings, to provide easy piggyback camera attachment. 182mm Diameter.