The Viqua 602810-102 Lamp and Sleeve Kit provides all the materials necessary for a successful bulb installation for the Viqua D, D4/PLUS, D4-V, IHS12-D4, IHS22-D4, as well as retired Trojan UV Max models C, C4, and C4-V. This kit includes the lamp bulb, quartz sleeve, and 2 o-rings for an all-inclusive installation experience. Buying these items together will not only save you money but will also leave you confident that you purchased all the correct parts for your system. The included lamp (model number 602805) provides protection from occasional intrusion by microbial contaminants including protozoan cysts, bacteria, and viruses. The included quartz sleeve (model number 602732) protects the lamp so it can purify your water thoroughly and without potentially costly interruption. During ultraviolet sterilization, the water is exposed at a controlled rate to UV light waves which deactivate the DNA of microorganisms, thus preventing them from reproducing. For optimum performance, replace the UV bulb every 9-12 months.