... API 11B sucker rod couplings, including Spray Metal coupling, class T coupling, Altra High Strength,Sub OD coupling, with various spec ... , Golden supplier of Alibaba.com and the best supplier you can trust in China.PRODUCT BRIEFThe SPRAY METAL sucker rod coupling ... of abrasion-proof, wear-proof and lessening friction coat. It can’t only protect itself but also the rod, preventing and slowing ...