... Material: AISI 5140 Coat Layer: Ni60A Yantai Yunsheng Petroleum Machine Accessories Co.,Ltd. produce API approved sucker rod couplings, ... , Class T couplings, Full size couplings and Slim Hole Couplings with the size range of 5/8", 3/4", 7/ ... Material: AISI 5140 2) Standard: API Spec 11B 3) Size: 5/8",3/4", 7/8", 1", 1-1/8" ... 4)Smoothness: 3.1×10-3 5)Coat Thickness(in): 0.01in ~ 0.02in 6)Basic ...