This carbon block cartridge is the postfilter for model CM-2 CTO. The radial carbon block design efficiently adsorbs chlorine / chloramine and other chemicals from water. The SQC(sanitary quick change) design allows for quick and easy cartridge change. The Water Factory 47-55708CM cartridge is made from FDA (CFR 21) compliant materials. Click here for information about the composite sediment pre-filter 47-55712CM. Click here to purchase the CM-2 CTO cartridge replacement set.