In order to improve ease of use of thermocouples, Ninomiya also offers light and flexible duplex-insulated thermocouple wires which are made of elemental thermocouple wires coated with insulation materials. If temperature in the contact, where terminals meet, changes in a closed circuit composed by two conductors made of different materials, thermoelectromotive force is generated and current runs in the circuit as the result of the Seebeck effect. Electrical connection with either such two different conductors (elemental thermocouple wires) for thermoelectromotive force generation purpose is called thermocouple. Elemental thermocouple wires are offered in extra length for making thermocouples. Users can cut it in the length as they like, connect a terminal electrically to make a pair of thermocouples. Duplex insulated thermocouple wires are thermocouple wires coated with insulation materials such as silicon-rubber, fluorocarbon-resin, glass fiber, silica fiber, ceramic fiber etc.