The Round Back Attic Fan is a small low profile residential powered vent. constructed of durable, rust-free aluminum, EXHAUSTS CONTINUOUSLY whether the electric motor is ON or OFF. On the days when the fan is not needed, the Round Back Attic Fan will still operate passively. The Inner louvers prevent the entry of rain, snow, insects and birds, while allowing the air to flow with no resistance. The 1/8th inch opening between the louver blades and all aluminum (“noncombustible”) material meets the requirements of California building code 706A.2 Vents to resist the intrusion of burning embers and flame through ventilation openings. Powder-coating is available in a wide variety of colors.