For sale is a Northfield 3 inch Grinding Chuck. It is a pneumatic chuck. This is about the most expensive, fast, and precise workholding solution out there. The chuck's OD is 3 inch. It has a mounting taper that resembles 5MT (MT5).
I tested it by hooking up to my compressor. When I engage the lever, the jaws close in, so very slightly. You get everything, chuck, regulator, air switch, oil, etc, but not the beer can.