Ultrapure 3901720 Replacement Lamp. This is a replacement lamp for Ultrapure UV technology. With systems designed to utilize various wavelengths of ultraviolet light, Ultrapure UV technology can be used for total organic carbon (TOC) reduction, chlorine/chloramine destruction, ozone destruction and microbial disinfection. These products are recommended as part of a larger treatment system, as they work to enhance other methods, including water softening, water filtration, reverse osmosis, high-purity DI and electrodeionized water systems.