application : instrument . Thermometer bellows coupling bellows  fuel level gauge valve copper bellows  no sealing  high pressure bellows   vacuum bellows  sensor bellows  vacuum switch

types of joints :  1, both ends are external joints  WW type   

                            2, both ends are internal joints   NN type

                            3, one end is external joints , the other with bottom   WDtype   

                            4, both ends are side cut from the trough  QdQd type