Product 1290F is a cheap real spherical fire damper made and experienced for point-of-origin fire containment where by spherical ductwork passes as a result of metallic stud drywall partitions or masonry partitions that have a hearth resistance score of approximately 2 hours and making codes require a fireplace damper. Options https://heavy-duty-stainless-stee67789.blogdeazar.com/37236896/considerations-to-know-about-heavy-duty-stainless-steel-damper-manufacturers