Brief Introduction: it is mainly used in workover well to prevent blowout. Executive Standard: API16A;API6A Specification: Sucker Rod Size:5/8"~1 1/2" Nominal Diameter:2 3/8",2 7/8",3 1/2",4", 4/12"; Working Pressure:14 MPa,21 MPa,35MPa; Connection of top and bottom: API tubing thread :2 3/8"NU,2 7/8"NU,3 1/2"NU,4"NU, 4/12"NU 2 3/8"EU,2 7/8" EU,3 1/2"EU, 4"EU, 4/12"EU