... quality alloy steel with advanced heat treatment,and all size of sucker rod available in grade C,D,KD,H, L ... ,HY and This company is one of the main producers and providers of sucker rod in China, and get certificate ... Issued by American Petroleum Intitute and acquired ISO9001 Cetificate of Registration and became the firstfirm of passing "Dual Registration"by API in China. product ...