"Magnesium alloy, per QQ-M-55, circular shape with a 1.480-inch radius cutout and flats to the outer edge, 1.090 inch radius inner rim, 0.600 inch diameter, 0.060 inch thick, 2.180 inch inside diameter, holes at two places with 0.089 inch diameter tap and 0.112 inch -40 threads, 2.400 inch center-to-center hole across diameter, and a 0.780 inch center hole to flats"