The Middle Atlantic FC-4A is a proportional speed thermostatic fan control that extends both equipment and fan life and reduces service calls by varying the fan speed of up to four fans based on temperature. The fan control includes 3 user selectable temperature ranges, a local on/off switch, status LEDs, and a temperature probe with a 5ft wire. This control is designed to work specifically with AC fans that are offered by Middle Atlantic Products, or other fans with similar specifications.