Yunsheng is the manufacturer offering API sucker rod couplings in Shandong China. All the rod couplings are produced in fully accordence with API Spec 11B standard and manufactured with high quality Carbon steel AISI 5140. Our sucker rod couplings are very cost-effective, including class SM sucker rod coupling, class T sucker rod coupling, Sub sucker rod coupling, Full Size sucker rod coupling, Slim Hole sucker rod coupling. They are available in 5/8", 3/4", 7/8 ",1"and 1-1/8".