Ultraviolet Sterilizer add-on kit provides 100% protection against bacteria, viruses, cysts and pathogens in the product water. Great for well or surface water sources. Ensures the safest water. Includes stainless steel UV unit with Â¾" MNPT ports,Â wall mount clips and transformer. For use with Big Boy and most RO and filter systems with up to 8 GPM flow rates."