This kit includes the replacement UV UVMAX lamp bulb and accompanying quartz sleeve for the D, D4, D4+, D4-V, C, C4, C4-V and IHS (D4) Model 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. Additional Details ------------------------------ Product description: This kit includes the replacement UV UVMAX lamp bulb and accompanying quartz sleeve for the D, D4, D4+, D4-V, C, C4, C4-V and IHS (D4) Model 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.