5/8" 500-2M NATIONAL 3 SPLINE BACK SPOT FACER PILOT MT2
REVERSE SPOT FACER HOLDER. For use holding inverted spot facers or countersinks with #500-2M (1/2") National 3-spline drive. Arbor is #2 Morse taper shank. Made by National, patent 2120623. Marked "C" and "X".