... : 4120,4142,4330,4720,4620 3. Sinter bar,polished rod and subcoupling are avaiable. Description : Our Sucker rod produced according to API 11B specification ... shoulder(mm)Nominal Diameter of threadNominal Size of Sucker Rod length(mm)Pony Rod(mm)5/8"φ15.8831.815/16"7518,904250811181727233729463/4 ... HRC ≥42, center rigidity HB ≥224,quench rigidity depth 1.5~3.0mm sucker rod