All aluminum construction. Includes 8 in x 8 in perma-coated aluminum screen extended to the edges of the cap. Large nailing flange. Rolled flange on vent stack to prevent weather infiltration. A 550S with a taller throat for use on a shake roofs is available. 50 sq-in of net-free ventilating area. 15-3/8 in x 16-1/2 in x 4 in overall size.
