A 150mm twin wall to flex adaptor is a transitional piece used to connect a twin wall flue system (a double-walled, insulated chimney pipe) to a flexible flue liner. This is necessary when a stove or appliance flue needs to transition from the twin wall system to a flexible liner within the existing chimney structure.
The adaptor has a screw fix coupling that screw onto the flexible flue liner. This transition must be made inside an existing class 1 Chimney. (no flex should be visible outside the brick or clay chimney.