HIGH GRADE CARBON STEEL-GRAPHITE COATED.  MILLED BY SPECIAL COATED PROCESS TO ASSURE PERFECT SHAPE.  GREATER RESISTANCE TO SHAFT FRACTURE DUE TO KEY SEAT AND PERMANENT KEY FIT.  EASE OF ASSEMBLY AND DISASSEMBLY OF KEY IN KEY WAY DUE TO FLAT BOTTOM AND STARTING RADIUS.  EASY REMOVAL BY TAPPING ON ONE END UNTIL THE DISPLACEMENT ALLOWS THEM TO BE LIFTED FROM THE SEAT.