Trolmaster Fan Control AdapterTROLMASTER FAN CONTROL ADAPTER If you're using the Tent X Control System to control an EC Fan, the TrolMaster EFC 1 is the perfect accessory. It's designed to regulate the fan's variable speed, and you can select either PWM or 0 10V output modes to control it. For each Tent X, you'll need a corresponding EFC 1 for both Exhaust (F1) and Intake (F2) lines. That means one EFC 1 is required for each Exhaust (F1) or Intake (F2) line. KEY VALUES LCD Display