This adapter works in conjunction with extractor fans, tumble dryer vent hoses, and other venting systems to ensure efficient ventilation Make from this adapter is designed to last through harsh conditions like kitchen and bathroom This rectangle to round duct connector allows for easy installation on existing systems Flat duct adapter provides smooth airflow from 115mm x 50mm rectangular to 4" round ducts To enhance ventilation in bathrooms, toilets and utility rooms and maintain complete air circulation