Domed quartz sleeve for the Hanovia WS216 disinfection system, 884 mm long, part 320203-0840. 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. Domed means the sleeve is closed with a formed hemispherical end rather than being open at both ends — a domed sleeve is not interchangeable with an open one, because the closed end is what allows the lamp compartment to stay dry with only one seal. Supply the seals separately if the existing set has been in service. Reference number 22116-0115.