Yantai yunsheng petroleum machine co.ltd

We'r professional manufacturer of API Sucker Rod Coupling in China.Our sucker rod couplings includ class SM coupling, class T coupling, Sub coupling, Full Size coupling, Slim Hole coupling API Coupling, class SM 1Material: AISI 5140 (40Cr)¿AISI 413(35CrMo), 2Standard: API Spec 11B 3Coat Thickeness: 0.01-0.02 in 4coupling diameter: 5/8 ",3/4",7/8",1",1-1/8" 5Basic Hardness: HRC 16-23 6Min.Metal coating hardness: 595 HV0.2