... couplings for oilfeild 2.Std Ref: API 5CT 5B 3.Grade: J55,K55,N80,L80,C90 4.Feature:good sealing Detailed ... .90*234.9515.637-5/8"STC215.90*263.5215.828-5/8"STC244,48*196.8516,238-5/8"LTC244,48*254 ... .0021.678-5/8"STC244,48*269 ... .8820.869-5/8"STC269.88*196 ...