Product details:
Honeywell 20 in. x 12 in. Parallel Blade Damper ZD20X12TZ The ZD is a power close and spring open damper. It has a 24-volt motor used to control circulating air in HVAC systems and used when a normally-open damper is required. The ZD is typically used with the TrueZONE and other electronic zoning systems.