Astria Outside Air Kit for See-Through Gas Fireplace FOAK-4LDAstria Outside Air Kit for See Through Gas Fireplace FOAK 4LD Product Details What role does the Astria Outside Air Kit play in enhancing the performance and efficiency of a see through gas fireplace, and how does it contribute to better air quality and combustion? Astria Outside Air Kit Key Features For use if outside combustion air is required or desired. Must be used in conjunction with locally purchased, non combustible Class 1 or Class 0 flexible