Yunsheng Sucker Rod Coupling are manufacturer from high quality Alloy Steel AISI 5140,fully in accordance with API Spec 11B standard ,inclding class SM coupling,class T coupling,Sub coupling,Full size, Slim hole and Over Size. Main Couplings list Name Size Grade Characters Remarks Sucker Rod Coupling5/8¡±; 3/4¡±;7/8¡±; 1¡±, 1_1/8¡±T, SM Including the following SM Coupling, T Coupling, and SubCoupling SM Coupling5/8¡±; 3/4¡±;7/8¡±; 1¡±1-1/8¡±