This kit includes the replacement UV lamp bulb and accompanying quartz sleeve for the obsolete VIQUA Sterilight SPV-3.5, SPV-200, SP200-HO and SC/SCM-200 Series UV systems. It is extremely important to replace the bulb every 12 months to maintain proper system efficacy. The sleeve can be replaced every 24 months or as needed to keep mineral build-up from hindering the lamp's effectiveness.