The rod thermostats are fitted with liquid-filled probes made of copper that act as temperature-dependant pressure probes. A change in temperature causes a pressure change in the probe, which is transferred to a switch by a bellows system. A compression spring acts as a counteracting force. The switching values are set by changing the initial stress of the compression spring with a setpoint spindle. A thermowell with R 1xternal thread made of brass or stainless steel (optional) is part of the scope of delivery. The rod thermostats are available with adjustable switching difference or temperature switch, temperature controllers and safety temperature limiters according to DIN 3440.