Quartz sleeve for the Hanovia QMB100B/1/4/MHX medium-pressure disinfection system, 360 mm long, part 320204-0360. 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. A sleeve is replaced when it is cracked, etched or permanently fouled — etching and scale that will not wipe off cut UV transmission just as effectively as a failed lamp, and are a common reason a system reads low dose on a new lamp. Reference number 2283-0211.