Orion 7373 140mm ID Telescope Tube Rings Set of two cast-aluminum telescope tube rings with quick-release, hinged clamp knobs and felt lining Inside tube ring diameter is 140mm, use with telescope optical tubes up to 140mm in outer diameter Sold in sets of two rings Mounting bolts and washers are included One ring has 1/4"-20 piggyback camera adapter; the other has threaded 1/4"-20 hole