APi 5ct casing pipe threads: stc,btc.ltc,xl(extrime line) Certificate; API-5CT1188 API-5DP0085 APi 5ct casing pipe threads: stc,btc.ltc,xl(extrime line) Certificate; API-5CT1188 API-5DP00851.Size : 4 1/2"----20" 2.standard: API SPEC5CT 3.High quality, Competitive price,Best service. 4.It is used for extracting oil or gas from wells.