The Orion 140mm ID Telescope Cast-Aluminum Tube Ring set features quick-release hinged clamp knobs and felt lining. Designed for use with Orion mounts, they fit some other brands of mounts as well. One of the two rings in the set has a 1/4"-20 piggyback camera adapter on it, the other has a threaded 1/4"-20 hole.
The piggyback camera adapter can be removed for mounting an adapter plate for a guide scope on top of the tube rings. For use with SkyView Pro or Atlas mounts, you will also need a dovetail mounting plate, #7383 (8" length) or #7385 (13" length). Set of two rings includes mounting bolts and washers.