I got this in a trade recently and have no use for it. It's an extra large Tele Vue Gibraltar head. The previous owner said it would hold up to a 6 inch refractor, and was originally made for the Tele Vue NP127 (I can't confirm that). The inside width is 6.875" and the depth to the bearing center is 3.5". A "regular size" Gibraltar head is 5.375" wide and 3.0" deep to bearing center. I have both heads and measured them side-by-side. This oversized head also has been modified with a 0.375 thick plate on the bottom of the yoke stamped "KD". This mod was done by Ken's Rings, and according to the previous owner it cost over $200 for this mod alone. I can make more measurements or take more pictures if you're interested. Good used condition showing some signs of use, and there is some white residue on the brass bearings, but should clean up fine.