Manual duct damper for round ducting (balancing damper) with handle. Balancing damper made of heavy duty galvanized metal. Also called spool damper or volume damper.  Available in 6", 7", 8", 9", 10" and 12"  and made out of 26 gauge metal.

Heavy Duty Manual Zone Damper For Air Control And Balancing

• Manual duct disc damper for round ducting with handle
• One end Crimped for Installation
•  Made of heavy duty galvanized metal