Used on hardware;sub engineering & diesel sys. ring, packing (0.156 pitch 12 tooth) 10.000 in dia; temp 0-350f deg; 12 holes eq sp, 5/8 in dia counter bored 0.740 in deep, along the side of packing; holes centered 30 deg apart center to center; (a) dia 7.811, (b) dia-8.001