Yantai Yunsheng Petroleum Machine Accessories Co. Ltd., founded in 2005, is a professional manufacturer of API Spec 11B Sucker Rod Couplings, including Spray Metal coupling, class T coupling, Sub OD coupling, with various type of Full size, Slim Hole, Over Size, with Big Chamfer, with Wrench Flat, with Bidirectional Cambered Surface Protection, etc., and the thread size are available at 5/8”, 3/4”, 7/8”, 1”, 1-1/8”. Owning world top level equipments and technicians, the monthly production capacity is more than 20,000pcs. All of our couplings are excellent in Quality and reasonable in Price, and the production & inspection are being done fully in accordance with API Spec11B standard.