' Oil Hard, Drill Rod, Steel Material, Fractional Size 9/16 In., Decimal Equivalent 0.5625 In., Dia. Tolerance +/-.001 In., Finish 20 RMS Max, Length 36 In., Length Tolerance +.125 In./-.000 In., Hardness Scale 241 BHN Max, Grade O1, Standards UNS T31501, SAE J437, ASTM A-681-94, FEDERAL QQT-570 REV C '