duMONT Minute Man® Keyway Broaches and Bushings have letter designations signifying the body width of the Keyway Broach and the guide slot in the Bushing. The Bushing size and Style are determined by the bore diameter of the workpiece as well as the Style of Broach to be used. “A” Style Broaches are used with “A” Style Bushings, “B” Style Broaches with “B” Style Bushings, etc. duMONT Collared Bushings are “A”, “B”, and “C” Style while “D” and “E” Style Bushings are Plain. “F” Style Bushings are Plain and though considered Special are often available from stock.