Nailor 1500 Series Heavy Duty Control Dampers feature heavy duty galvanized steel U-channel frames, adjustable face linkage, and stainless steel pivot pins which results in smooth operation and easy maintenance. Designed for "in-duct" mounting applications to control airflow and provide positive shut-off. Dynamic limitations: Pressure: 2.9-20.1" w.g. and Velocity: 3000-3500 fpm (Vee Blade Models) and Pressure 10.0-32.0" w.g. and Velocity: 4000-6000 (Airfoil Blade Models)