Ggun metal ; 4.110 inch to 4.125 inch outside diameter; first recess inside height 0.529 inch to 0.559 inch ; flange thickness 0.157 inch to 0.167 inch ; 2.860 inch to 2.890 inch first recess diameter; 3.143 inch to 3.145 inch second recess diameter; 1.531 inch to 1.536 inch hole diameter; six 0.322 inch to 0.332 inch diameter holes equally spaced, counter sunk far side