Pressure Relief Horizontal Air Up 3520-18X16 T-Bar Standard Features 1” rim size

Standard Features 1” rim size (2” larger than nominal duct size / order size) 14 gauge steel construction Countersunk mounting holes for a flush appearance 1-27/32” Wide x 11/32” High slots on staggered centers

Concealed mounting holes with mounting screws

Standard Features *Surface mount return air grille * 45 fixed blades parallel to longest dimension * Countersunk mounting holes for flush appearance with color matching Phillips posi-drive screws * Soft White Options * 935 O - recessed screwdriver operated opposed blade damper * No Labor Collar (square sizes only) * 900 T - T-Bar mount * 905 HD - reinforced construction * 905 IS - insect screen * 1335-1338 Series - stainless steel version * Tamper proof screws

Standard Features * Field installable butterfly damper * Available in sizes 6

Holds up to a 2" filter (not included) with filter retention tabs (FG2)

Pressure Relief Horizontal Air Up 3520-18X16 T-Bar Standard Features 1” rim sizeh3. 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