Pressure Relief Horizontal Air Up 3520-12X24 Accessories 12" and 14") * HVD

12" and 14") * HVD OR - factory installed opposed radial damper (sizes 6"-14") * HVD FR - U

904 - Double Deflection Adjustable Aluminum Blade Grille For a 20" x 12" Duct Opening (front blades parallel to shortest dimension)

22 gauge butterfly style galvanized steel blades

Designer Color or Satin Anodized Finish available on this product

7/8” Wide x 7/8” High square holes

Pressure Relief Horizontal Air Up 3520-12X24 Accessories 12" and 14") * HVDh3. Standard Features * 3510 Vertical mount * 3520 Horizontal mount air up * 3530 Horizontal mount air down * Designed to open with negative or positive pressures for intake or exhaust air * Felt edge blades to hold noise to a minimum * Aluminum construction * Blade to blade linkage * 1 4" pivot pins in nylon busings * Maximum size 24 x 24 * Mill finish h3. Options * Sleeve variations * Mounting flange * Adjustable counter balance to adjust various