Goes along with the interior flange and interior locking band (with centering extension). The outer locking band is on the skin For additional assist, making it a more powerful method. Grease duct is either routed via a fire rated shaft enclosure or wrapped having an approved fire insulating blanket that https://greasetightextractductwor35677.blogoxo.com/37101467/fire-resisting-ductwork-insulation-things-to-know-before-you-buy