Heavy duty motorized volume control dampers. The 1-1/2" flanged frame has welded corners for added strength. The 6" wide blades are center-pivoted for a full 90 degree rotation with parallel blade action. The stainless steel jamb seals help in keeping out light, air, and moisture. The dampers can be used for exhaust or supply applications and can be mounted in either a vertical or horizontal position; typically walls or curbs. Comes standard with an internally mounted factory installed 100-240 volt power open / spring close motor with end switches.