Customers can automatically reduce heating and cooling inefficiencies in their home and indoor garden with ZoneMaster Dampers. Once installation and wiring are complete, the damper will open and close to allow airflow according to predetermined temperature triggers. With one crimped and one straight duct end, this non-directional twelve-inch damper is easily secured into existing ventilation duct work of the same size. A UL-Listed transformer is also included and must be wired to a remote thermostat (available separately) for the unit to operate correctly. ZoneMaster Dampers are made in the USA and covered by a three-year manufacturers warranty.