UL Design and style 563 = Optional ceiling damper (seek advice from manufacturer for information on this type of damper). Unless you ran your kitchen exhaust in rigid fiberglass duct board or UL mentioned factory manufactured air duct there wouldn't be a necessity for the use of UL 181A or https://rockwoolinsulation27047.liberty-blog.com/35439052/the-best-side-of-calcium-silicate