4 Inch Backdraft Damper, Stop Backdraft, Bugs & Fire Hazards, for Ventilation System

Male backdraft shutter is lightweight & compatible with Hon&Guan ducting.Easy to DIY. Designed to provide anti back draught, and fit in between Solid Plastic Ducting, Flexible Ducting.Application in domestic ventilation; kitchens, toilets,bathrooms & hydroponics.