6cres per ams5610, immunize per bendix specification no. Es-091, 26 to 32 hardness rating, rockwell c scale, bright finish all over per bendix specification no. Es-0521, 1.06 in. Lg, 0.305 in. Min, 0.315 in. Max hex od, 1/8&40 unc-3a thd per bendix es-0431 except od of thd