The Sterilight SC200-A UV system disinfects all the water entering your home and provides protection from bacteria and viruses in your water. In order to maintain the manufacturer's warranty, UL third-party certification, and ensure your Aquasana AQ-UV-STD Sterilight UV system is properly treating the water in your home, it is necessary to only use genuine VIQUA Sterilight S200RL-HO (formerly AQ-UV-STD-LAMP) UV lamps in your system. Genuine manufacturer lamps will have "VIQUA S200RL-HO" etched onto the lamp glass. Using any other lamp will void the manufactures warranty and may be unsafe to use.