[Premium Material]:Duct Manual Volume Damper is made of PVC material,with reliable quality,wear resistance and long service life [Easy to Use]:Backdraft Damper,no power supply required,easy to operate,you can adjust the air volume at any time [Application]:PVC Regulating Valve is suitable for various duct systems and is an ideal choice for commercial or home ventilation and exhaust systems [Easy to Install]:Round Volume Damper,simple and convenient installation.Switch valve design,easy to switch. [Professional]:Air Ducting Branch Vent Damper Air Control Valve can help you accurately control the air volume and achieve good ventilation effect, Manufacturer: N\A