The quartz sleeve separates the ultraviolet lamp from the water while passing UV-C into it. Length and glass grade both identify a sleeve — length alone does not, and this catalogue stocks more than one sleeve at several of these lengths. This is the 867 mm sleeve in F240 grade. Berson's 867 mm position is also stocked in standard grade under item 1016-0504 at a lower price; the two are dimensionally alike and optically are not, so order against the grade the reactor was specified with rather than against length. The corresponding Berson OEM sleeve at this length is 2.55.028.