3 Jaw Self Centering Chuck With Backplate & Tee Nuts for 3" & 4" Rotary Tables Quality 3 jaw self centering chuck 65 mm Diameter Contra rotating rapid jaw adjustment mechanism. Backplate is drilled and counterbored to fit a range of 3” and 4” rotary tables with 3 Slots or a 4 Slots Supplied complete with a key as well as set of tee nuts and studs to secure it into place.