pipe coupling, casing coupling Sizes range from 2 3/8" to 13-3/8". Steel grade including :K55, J55,L80,N80,C90,T95 and P110 pipe coupling, casing couplingSizes range from 2 3/8" to 13-3/8".Steel grade including :K55, J55,L80,N80,C90,T95 and P110Thread types :STC, LTC and BTCQuality is fully guaranteed. coupling