????????????? Yantai Yunsheng Petroleum Machine Accessories Co., Ltd., is a modern high-tech enterprise specialized in manufacturing petroleum machine accessories--sucker rod coupling . The company can itself research and develop to produce the Deflection-proof and Abrasion-proof Sucker Rod Coupling，Common Coupling and Sub couplings,which have passed the ISO9001 and API SPEC11B Quality Management System Certifications，Industrial Production Permit of China，and Import& Export Licence. The excellent value for money makes Yunsheng Petroleum Machine Accessories enjoy high and long-standing reputation home and abroad.