Air release valve cracked or leaking? Replace it to ensure that your cartridge filter is properly pressurized and to prevent accidents! The Waterco Trimline Cartridge Filter Air Release Bleed Valve is manufactured from heavy duty PVC plastic, ensuring all replacement parts and equipment is tough, chemical resistant and UV stabilised to last in harsh Australian conditions for years of use. Suits: Waterco Trimline Cartridge Filters Includes o ring Genuine part number 620221