Since the resistance change of strain gauge is very small, it requires a Wheatstone bridge circuit to measure strain with strain gauge. The simplest method is to place a strain gauge into one arm of bridge circuit, while placing fixed resistors into other three arms. This method is called a quarter bridge method. If 3-cored lead wire is used for connecting a strain gauge, influence of resistance change of lead wire due to temperature change is cancelled. This is called a quarter bridge 3-wire system. Half bridge is a method to place strain gauges into two arms. This method has the advantage of doubling the output voltage or compensating the thermal output of strain gauge, depending on the conditions of strain gauge application. Full bridge method, in which all four arms are replaced by strain gauges, yields redoubled output and compensation of temperature effect. TML strainmeters have functions of arranging bridge circuit, applying excitation voltage and amplifying and reading output voltage.