The combination temperature controller/safety limit switch MT-1 provides 1% accurate snap-action control over a range of 0Yê to 500YêF (-40Yê to 260YêC). No external calibration devices are required. The unit operates on the basis of deflection created in a probe comprised of two materials that have differing rates of thermal expansion. The motion created by the slight deflection that results from a change in temperature is translated from the probe to the switch, opening or closing the circuit it controls. The large, 1-1/4-in. diameter, easily accessible dial provides both temperature readings and set point adjustment.