The connectors spacing of this series is 4.5m, these connectors with the PCB of 2±0.15 mm thickness are used for connection of printing circuits. FQN series internal-bayonet waterproof circular connectors are ideal product of a new generation to replace FQ series connectors. The installation size and arrangement of contacts are as same as the products of FQ series. Those connectors have the features of high reliability, environment resistant, high sealed characteristics, plugs and receptacles quickly mating and unmating, user-friendly and easy to use and so on. They are widely used for the electric circuit connection between electrical equipment and various electronic equipments.