Pressure Relief Horizontal Air Up 3520-16X12 past 12 months 904 - Double Deflection Adjustable

904 - Double Deflection Adjustable Aluminum Blade Grille For a 30" x 20" Duct Opening (front blades parallel to shortest dimension)

available 4" through 40" round (2549)

904 - Double Deflection Adjustable Aluminum Blade Grille For a 14" x 12" Duct Opening (front blades parallel to shortest dimension)

Non-standard size collar (available in 6" through 20")

Designed for ceiling or sidewall applications

Pressure Relief Horizontal Air Up 3520-16X12 past 12 months 904 - Double Deflection Adjustableh3. 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