Replacement quartz sleeve for Hanovia medium-pressure ultraviolet disinfection systems, part 320193-0558, 558 mm long. The quartz sleeve is the pressure barrier between the treated water and the lamp, and the only optical path between them, so it must both hold system pressure and pass UV without loss. The 0558 group in the part number is the length in millimetres, which is the quickest way to confirm a sleeve against a system before ordering. Reference number 2207-1205.