White Rodgers 903992 is a heating and cooling thermostat designed for use with gas or oil heat and central air conditioning. It features four-wire, single-transformer systems and two-transformer systems. It has adjustable heat anticipation from 0.15 to 1.2 amps. The thermostat also includes a fan switch to control fan operation, with options for AUTO, ON, and OFF. It is easy to operate with a slide temperature lever and system switch to select heating, cooling, or off.