The A421 Series Electronic Temperature Control is single-stage with a single-pole, double-throw (SPDT) output relay. It features a backlit LCD with adjustable brightness and three-button touchpad interface that you can set up to restrict user adjustments. An LED indicates the output relay's on and off status. It has a simple on and off temperature settings for heating or cooling, an adjustable anti-short cycle delay, temperature setback, and sensor offset capability. The temperature control range is -40 degrees F to 212 degrees F or -40 degrees C to 100 degrees C.