Wall Shutters Wall Shutters Flo Master end wall vent on Quonsetter for seed production house Jacklin Seed Flo-Master Aluminum Wall Shutters Corrosion resistant heavy gauge aluminum frame. Precision counterbalanced aluminum blades open easier, wider to permit higher fan capacity. Nylon bearings throughout are corrosion proof to help prevent sticking. Suitable for dusty or humid applications. Stainless steel hinge pins will not rust, insure easy positive blade action. All shutter blades are reinforced with polished galvanized steel rods, and equipped with double tie – rods. Automatic – Used with exhaust fans, opens automatically when fan is on, closes automatically when fan is off. Keeps out wind, rain and back drafts when fan is not in operation.