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. This is the QM203 sleeve for the TE900, 1056 mm long. Wedeco was founded in Herford, Germany in 1976 and is now a Xylem brand.