Galvanized Commercial Industrial Large Barn Vents, Industrial Building, Warehouse, Manufacturing Excess Heat, Ventilation, Commercial Buildings, The Benefits include Heavy Long Lasting Thick Gauge Stainless Metal, Draft Inducing Caps, and our Rain, Wind and Weather Proof Designs. Sizes avialable in 4 inch, 6 inch, 8 inch, 10 inch, 12 inch, 14 inch, 16 inch, 18 inch, 20 inch, 24 inch