' Water Hard, Drill Rod, Steel Material, Fractional Size 5/8 In., Decimal Equivalent 0.6250 In., Dia. Tolerance +/-.001 In., Finish 20 RMS Max, Length 36 In., Length Tolerance +.125 In./-.000 In., Hardness Scale 241 BHN Max, Grade W1, Standards UNS T72301, SAE J437, ASTM A-686-92, FEDERAL QQT-580 REV C '