All of above products are produced and processed according to,with materials of steel grade including J55,K55,N80,N80-1,N80-Q,L80,P110 and so on.The tubing couplings have two types,namely NU and EU.By numerically controlled lathe and import molding cutter,the processing of thread can be finished in one time,which ensures its commonality and interchangeability.we have complete testing abilities,adopting a whole set of single testing apparatus of thread,including tape、pitch、tooth depth and profile.Our products have already passed the identification of the Quality Testing and Inspection Center of Oil Pipe of CNPC(China National Petroleum Corperation).The pup-joints'any size,length,grade and weight is available on customer request.