Nailor Product 0722 Ceiling Dampers are for use in spherical programs, in lieu of hinged door kind dampers in almost any UL/ULC flooring/ceiling or roof/ceiling assembly with approximately a 3 hour fire resistance ranking the place air ducts are permitted. 1210SS Series dampers are intended and tested to offer premium effectiveness and gives the bottom https://heavydutystainlesssteelda57789.blazingblog.com/36974993/the-smart-trick-of-heavy-duty-stainless-steel-damper-manufacturers-that-nobody-is-discussing