EFC-1 is specially designed to be used with Tent-X Control System to control the variable fan speed of the EC Fan. The EFC-1 needs to select the mode of output to control the EC Fan in PWM or 0-10V. Each Tent-X can connect a corresponding EFC-1 for Exhaust (F1) and Intake (F2). Each Exhaust (F1)/ Intake (F2) line requires one EFC-1.