This stainless steel counterweight was designed to fit onto the 2.5" diameter shaft of the 3600GTO and 3600GTOPE Mounts. It features a spring-loaded, recessed lock knob and measures approximately 8.0" in diameter by 2.6" thick. These are 0.10" larger in diameter and 0.10" thicker than the original 30 lb counterweights than we originally offered. Like the original, it machined from 303 stainless steel. The weights slip easily onto the counterweight shaft and are secured in position with a large hand knob/brass pin assembly. The brass pin will not mar your shaft.
Please note that the knob of the 33 lb. counterweight is slightly different than shown in the photographs.