ZONEMASTER ZONE CONTROL DAMPERSControl Airflow To Individual Rooms The ZoneMasterTM Zone Control Damper saves money on heating and cooling by controlling temperatures in individual rooms.• Available in 6, 8, 10 & 12 diameters. • Safe, low voltage stud mount transformer and motor• Tremendous energy saver• Free-wheeling coupling between motor and damper shaft for long life• Housing length is 8• 3 year limited warranty Includes 24v-120v transformer