150mm Extractor Fan Backdraught Shutter , back draught shutter

150mm Extractor Fan Backdraught Shutter , back draught shutter Features: 1. Made of stainless steel. 2. The outlet sizes choice : 100mm, 125mm, 150mm, 200mm, etc. Benefits to set this product to the ventilation pipe: prevent outside air from penetrating the home. prevent the smoke from public pipe enter into the home. prevent insects fly or climb into the ventilation pipe.