Optimum tower vent for use with our 20W106 solar attic fan system. Kit includes an adjustable tower and a bottom mounting plate for pitch adjustment. The OptiFLEX retrofit kit for mounting a solar panel on the vent top is sold separately. Vent is constructed of heavy-gauge galvanized steel with corrosion-resistant baked coating. Overall dimensions are 19.5 x 19.5 x 21 in. (495 x 495 x 533mm.). Designed for climates with heavy snowfall, providing 10-12 inches of clearance beneath fins.