Half-ring w/locking hub centered on entire outer circumference; 11.250 in.Od w/hub, 10.625 in.Od w/o hub, 5.031 in.Id, 1.375 in.Thk o/a, two 0.750-10 unc mtg holes, spaced 8.500 in.Apart on each side of id through thickness, 1.375 in.Dp; used on high pressure forward units, port and starboard