Help your Active Air fan operate at its most efficient and effective capacity by installing a corresponding Active Air flange. Available in sizes that match our entire line of Active Air filters, the flanges include sealing foam and six screws for an easy fit. Flanges connect to ducting, not directly to the fans themselves. Regular flanges come in 4", 5", 6", 8", 10", and 12". Wide-mount flanges are also available, in 6" and 8" sizes for specific Active Air filters. Don't lose valuable air cooling or invite in dust, dirt, and other airborne particules -- create a secure connection with your Active Air flange.