I have a brand new field tripod adapter for sale. Shortly after purchasing it and before I mounted it on a pier I received notification that my name came up for an AP1200GTO. I purchased it for use with my G11 on a permanent pier. It is 6.0" in diameter and is 4.0" high. The inside is machined to fit G-11 and GM-8 mounts. The tube has a 1/2" thick bottom with a 1/2" hole in the center. Posts for the electronics are mounted on the side. I'll sell it and ship anywhere in CONUS for $70.00.