3 Hour Out Of Air Fire Door Grille 2663-20X10 T-Bar 3% maximum leakage with a

3% maximum leakage with a pressure differential 3" W

stair risers

Blades parallel to shortest dimension

904 - Double Deflection Adjustable Aluminum Blade Grille For a 24" x 4" Duct Opening  (front blades parallel to shortest dimension)

Galvanized Finish

3 Hour Out Of Air Fire Door Grille 2663-20X10 T-Bar 3% maximum leakage with ah3. Standard Features * 2661 Square or rectangular fire door for vertical mount only. Maximum dimension 60x60. For damper free area chart A click here * 2663 Out of Airstream fire door. Square or rectangular for vertical mount only. Maximum dimension 60w x 52h. For damper free area chart B click here * 2665 Round fire door for vertical mount only. Available 4" thru 52" round. * 3 hour rated * UL and California State Fire Marshall approved * 4 1 4"