The eTRON M is a compact, digital electronic thermostat for simple temperature control (heating or cooling). The temperature is acquired through the packaged Pt100 RTD temperature probe in 2-wire circuit and visualized on a 3-digit backlit display. The switching status is indicated via an LED.  The version with two relays incorporates a simple defrosting function and a service hour counter which can, for instance, record the operating time of a cooling compressor.  Operation of the unit is from 4 keys on the front panel and electrical connection is by screw terminals on the back.