Activated Carbon filters can trap and absorb organic chemicals and chlorine from the water effectively with its ability of mechanical filtration and physical adsorption. It can efficiently remove odors and improve water taste. RO CTO Carbon Block 10 for Under Sink / Manual Filters 10 Micron Filter-Suited/Compatible Only for Wall Hanging or Undersink RO Models.This Carbon filter removes chlorine,sediment,dust,odor,and organic chemicals. This Filter needs to be Fitted inside a 10 Standard RO Housing Bowl. What is CTO carbon block filter Under sink 10″ (CTO) Carbon Block filter element for Undersink 10″ Reverse Osmosis systems. This Under sink CTO cartridge filters removes impurities from the water, thus preventing the RO membrane from getting chocked.How To Change CTO Filter Once you’ve taken the canister (Pre-Filter) off you can simply. Pull the filter out discard it grab the new filter. Place. It back in. And you can of course pull the water out that’s in there if you’d like.