... :300-1250mm 2.Carbon layer thick: 35mm,50mm Active Charcoal Air Purifier, Air Filter *Carbon layer thickness: 35mm, 50mm *Color available: Black, Grey ... prevents the formation of preferential channels which can allow untreated air through the system. And Housing Material is Galvanised steel & high ... duty hanger, Flexible duct...Rope Ratchet Filter Hanger Active Charcoal Air Purifier, Air Filter