The Ross 150 Roof Vent is a patented, static, exhaust roof vent that has been tested and proven to perform. It is Miami-Dade, TDI & FBC approved and is the only vent to pass the UL 2218 hail impact test. With 150 square inches of NFA it allows for fewer roof penetrations resulting in savings to the contractor in time and money. All Ross Vents offer the most NFA in their category and are designed using recycled no-break polypropylene making them virtually indestructible and classifying all Ross Ventilation products as GREEN. For more information, visit http://www.rossmfg.com/.