Half-ring w/ locking hub centered on entire outer circumference; 12.750 in. Od w/ hub, 12.250 in. Od w/o hub, 6.094 in. Id, 1.375 in. Thk o/a, 0.562 in. Thk hub; two 0.750-10 unc mtg holes, one on each side of id through thickness, 1.375 in. Dp; u/o low pressure forward units, port and starboard