... by high 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 of Authority to Use ... in China. product gradeC,D,KD,H, L,HY and Polished roddiameter(mm) 5/8"3/4 "7/8 ...