That would an external spline drive socket. Depending who sells it, it could be an ex160, x16 or something like that. Any auto parts store should be able to sell you one. I tried one (Snap-on ver) on my 11lb Walton stuffer using a 3/8 sq - 1/4" hex drive and powered it with a Milwaukee 90 degree M12 drill motor. You have to be careful because it makes stuffing casings as fast as lightning (almost). it does work however. I will say, the new stuffers with the handles on the side instead of the back where most have been placed for the last hundred years , is very awkward to use. Good luck!!