SYSTEM 204 DOUBLE AIRBRICK ADAPTER   The DUCVKC5633G 204x60mm Rectangular Double Airbrick Adaptor is manufactured from (white) High Impact Polystyrene and has a minimum free area of 15,360mm². It has a female adaptor for connection outside of the Kair System 204 duct. The DUCVKC5633G is fully compliant with SAP Appendix Q Product Characteristics Database recommendations for duct sizes used with both extract and Mechanical Heat Recovery Systems. DUCVKC5633G is manufactured in compliance with Domestic Plastic Ductwork Specification DW/154 and does meet UL94HB flammability standard. DUCVKC5633G has been designed for use with Kair System 204.