Replacement UV bulb ONLY for APEC ROES-UV75-SS with serial number AZ-UVSS-2500 and above or APEC ROES-PHUV75 with serial number AZ-PHUV-3000 and aboveContinuous UV Sanitization Provides Chemical-Free Purified Drinking WaterDestroys Up To 99.99% Of Bacteria, Viruses & CystsLow Cost Yearly Replaceable LampFeatured natural quartz sleeve to protect the lamp and allow the maximum amount of UV rays to penetrate and disinfect the water UV SanitizationUV disinfection is an all-natural process that does not change the composition of your water in any way. The germicidal energy of ultraviolet light destroys illness-causing microorganisms by attacking their genetic core (DNA). This powerful dose of UV light (wavelength of 253.7 nanometers) eliminates their ability to reproduce, and the organisms simply die. Water is purified by running it through a watertight chamber that contains an ultraviolet lamp. As water flows past, microorganisms are exposed to a lethal dose of germicidal UV energy. Disinfecting your water with ultraviolet light is exceptionally effective and environmentally safe. The UV does not change the taste, color, or odor of water. It is well proven, and it is the way of the future for water disinfection.