4die cast zinc alloy, 3.500 in. Min 3.510 in. Max dia, 0.350 in. Min 0.360 in. Max thk, 2.985 in. Min 2.995 in. Max step dia, 3.005 in. Min 3.015 in. Max diameter by 0.156 in. Min 0.161 in. Max deep center cutout, 0.266 in. Diameter center hole, marked 5 and 25