... STC casing couplings 2.Ref std: API 5CT 5B 3.Grade:J55,K55,N80-1,N80-Q,L80,C90, ... "BTC269.88*269.8823.1610-3/4"STC298.45*203.2020.78 10-3/4"BTC298.45*269.8825 ... .7411-3/4'STC323.85*203.2022.6411-3/4'BTC323. ... 85*269.8828.0313-3/8"STC365.12 ... *203.2025.6613-3/8"BTC365.12 ...