... ",Casing coupling fro4-1/2"to 13-3/8"4.Type: NU, EU(tubing coupling), STC,LC,BTC(casing coupling). 5 ... .Surface treatment: Whole phosphating, or inside phosphating and outside coating6.Packing: By carton, wooden case, wooden pallet, or ... by requirements of customers Our company manufacture and sell casing and tubing couplings,pup joints, tool joints, adapter pup-joints ...