The new modern way to vent bathrooms or dryers. No more wall or roof vents to leak or break. Mounts flush in soffit for virtually invisible installation. Meets all codes. Connects to either 4" or 5" ducting or flex hose. Flapper lets hot moist air out without letting cold air in. Overall size 6.75" x 6.75" x 5.75", 10 square inches.