This inline adaptor provides a smooth transition from 220 x 90mm rectangular PVC duct to 150mm round duct within the duct run. It allows the system to change profile where space constraints ease, or to connect with round fans, grilles, dampers and fittings. The gradual formed transition supports efficient airflow and helps avoid the leakage and turbulence associated with makeshift connections. Manufactured from durable, corrosion-resistant PVC, it is lightweight, easy to fit and suitable for concealed residential and light-commercial ventilation systems.