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. This is the 909 mm module for the SLR2581. The matching lamp is listed for the NLR2581 under item 1348-0307, and the SLR2581 ballast under item 13229-0615. Wedeco was founded in Herford, Germany in 1976 and is now a Xylem brand.