Orion 7372 116mm ID Telescope Tube Rings Set of two cast-aluminum telescope tube rings with quick-release, hinged clamp knobs and felt lining One telescope ring has 1/4"-20 piggyback camera adapter; the other has threaded 1/4"-20 acceptor socket Sold in sets of two rings with mounting bolts and washers included Use with Orion EQ-1, EQ-2, AstroView, SkyView Pro, Sirius, or Atlas equatorial mounts and SkyView AZ, VersaGo II, and Teletrack altazimuth telescope mounts Inside diameter of each telescope tube ring is 116mm