W.5CBHD American Plumber Carbon Block Filter CartridgeFor whole house applicationsEPA Est. Number 086074-WI-002Excellent for bad taste, odor, and chlorine taste & odor reductionNSF/ANSI Standard 53 certified to reduce cysts such as Cryptosporidium and Giardia by mechanical meansReduces particles as small as 0.5 micron in size by mechanical means