Abstract: Mechanical Building Code, Section 504.1, states “Clothes dryers shall be exhausted in accordance with the manufacturer's instructions.” Since at least one major manufacturer required at least one of the following, they've been incorporated into this product. 1. The opening must be sufficient so the exhaust flows unimpeded. 2. There must be 12 inches of unobstructed outflow upon leaving the hood. 3. There must be a damper. 4. There must be a wildlife barrier. 5. There can be NO SCREENS covering the exhaust port. Made by thermoforming ABS with a UV protectant, the DFP W1 Wall Hood is designed to fit over a standard four inch pipe where it exits a building on a vertical wall. Its opening has an area larger than a four inch pipe's. It directs airflow perpendicular to the building. Its damper flap completely covers the opening. The flap fits inside three ridges that prevent wildlife from opening the flap. No screens are used.