Resources Fan-Air GV Series Catalog     • 800 & 900 Series • 700 Series • 600 Series • 500 Series • GV Series • SE Series • UE Series     GV Series Gravity Ventilators & Fresh Air Intakes for Commercial, Industrial and Agricultural Requirements. Features:      • Aluminum and steel construction      • Standard 1/2" by 1/2" bird screen      • One year warranty Optional Accessories:      • Barometric back draft damper      • Backdraft damper with motorized actuators      • Control damper with quadrant handle      • Custom curb height      • Custom pitches      • Insect screen