"PLASTIC,NYLON CLASS 6/6,SPEC L-P-410; 3.094 IN. OUTSIDE DIA; 0.625 IN. INSIDE DIA AND COUNTER SUNK TO 1.250 IN. AT 30 DEG; 0.750 IN. THK; ITEM HAS FOUR MOUNTING HOLES DRILLED THROUGH AT 0.188 IN. DIA AND COUNTER SUNK TO 0.438 IN. DIA; COUNTER SINK OF MOUNTING HOLES BEING 0.219 IN. DEEP"