The Carbon Block Filter Cartridge(CTO) uses NSF certified high density activated carbon and harmless adhesive as main materials.  Its ash content is controlled to be the lowest to retain more effective micro-pores.  The large surface area has a tremendous capacity to absorb Chlorine, unpleasant odor, color, spore and remove lead and microorganisms.  The coconut shell activated carbon filter cartridge has a better filtration effect to the chemicals such as Trihalomethanes(THM'S)