Round damper, 18-inch, with 24-volt, spring return damper motor used to control volume of circulating air in heating, cooling, and ventilating systems. Galvanized steel, single-blade damper. Shipped as power closed/spring return open damper, for use with Honeywell Zoning Systems. Can be field-converted to power open/spring return closed damper when used as an independent zone or for fresh air intake. Blade closes off tightly against gasket for minimal leakage. Rated to operate up to 1 inch water column (wc).