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Feature
NOTE: Fits a 4" X 12" hole (see below for overall dimensions)Reinforced with pressure lock honeycomb construction to withstand heavy foot traffic
All extruded aluminum construction; 1/8" bars spaced on 1/2" centers, 0 deflection
Recessed screwdriver operated opposed blade damper to control air volume for positive balance
Positive volume set screw; Blades run parallel to longest dimension