The 4" Tele Vue Mount Ring Set provides a rigid and stable means of attaching any compatible optical tube assembly (OTA) to most mounts or heads. Its individual rings can be spaced from 5.5" to 6.5" apart to allows the Mount Ring Set to accommodate a variety of OTAs and mounts. Each ring has 2 accessory channels with #10-32 tapped holes, and 1/4"-20 tapped holes on the top and bottom of each ring to accept the accessory bar, the bottom plate, a stud, or a bolt as necessary. The included bottom plate is drilled to mate to a variety of mounts or mounting adapter plates, including Tele Vue's Vixen Mount Adapter and Gibraltar5 Head.