$22 The 801-10 is a 10 in. Butterfly air damper. The butterfly damper is used to cover duct openings in conjunction with a round air diffuser. Our product is constructed to help evenly spread out airflow from your duct opening. Using our product to outfit your ventilation system will improve your home and office air circulation.. Air deflection: Round. Color: White. Color Family: Whites. Features: Louvered. Installation Location: Ceiling. Material: Steel. Maximum Duct Opening Length (in.): 10 in. Maximum Duct Opening Width (in.): 10 in. Pack Size: 1. Product Weight (lb.): 1.3 lb. Returnable: 90-Day. Shape: Round. Outside Length (in.): 11.5 in. Outside Width (in.): 11.5 in. Maximum Duct Opening Length (in.): 10 in. Maximum Duct Opening Width (in.): 10 in. Installation Location: Ceiling.