The quartz module is the sleeve assembly supplied as a complete unit rather than as a bare tube — sleeve, seals and end fittings together, ready to fit. Ordering the module rather than the loose sleeve removes the two things that most often go wrong at a sleeve change: a seal reused past its compression set, and a sleeve loaded unevenly at assembly. The quartz sleeve separates the ultraviolet lamp from the water while passing UV-C into it. Length, diameter and wall thickness all identify a sleeve, and this catalogue stocks several at similar lengths — order against the reactor model rather than against a measurement of the old part alone. Wedeco was founded in Herford, Germany in 1976 and is now a Xylem brand.