... Carbon layer thick: 35mm, 50mm High Iodine Air Filter for Hydroponics Plant System *Carbon layer thickness: 35mm, 50mm*Color available: Black, Grey ... the system. And Housing Material is Galvanised steel & high impact polycarbonate cap. 3. ApplicationIt is used everywhere , including Grow tent ,hydroponics,greenhouse ... ... Rope Ratchet Filter Hanger High Iodine Air Filter for Hydroponics Plant System