They can be used for flue gas, ventilation ducts, etc.
Chimney Spark Arrestor Flue Liner Rain Cap Cowl Duct Pipe Cover Protector
Spark Arrestor Flue 60mm Stainless Steel, Tent Version
Chimney Anti-Wind Cowl Flue Liner Rain Cap Spark Arrestor Duct Pipe Cover
Chimney Anti-Wind Cowl Flue Liner Spark Arrestor Rain Cap Duct Pipe Cover
Chimney Anti-Wind Cowl Flue Liner Spark Arrestor Rain Duct Pipe Cover Protector
