Electronic ballast for Katadyn VR-series ultraviolet disinfection systems that are not built around the VG-64 ballast. That exclusion is the point of this part: VG-64 is itself a ballast type used with the K-64 UV lamp, so a VR system is supplied with one or the other and the two are not interchangeable. Establish which ballast the system currently carries before ordering. The ballast supplies striking and running current to the UV lamp; a failed one shows as a lamp that will not strike or that runs down on output while the lamp itself tests good. Reference number 11128-1114.