Aprilaire 6404 4-Zone Comfort Control Panel Any Zone Sets Mode, Provides true independent control for each zone Zone Changeover Based on Time LED Status Indicators are Visible through the Cover, these Allow your Customer to Aid in Troubleshooting Fan Purge Assures Air is Directed to Last Zone(s) Calling Short Cycle Protection, Protects the HVAC Equipment from too Frequent Cycles No Maintenance or Adjustments Needed After Installation Vacation Operation, Allows system to operate in setback from the thermostat designated Zone 1 when leaving