inline post carbon filter is the ultimate sweetener Crystal last post carbon filter: inline post carbon filter is the ultimate crystal, in the water, chlorine,color,taste and smell that gives the solution of gases,for refining of residues and organic substances is used. This granular activated carbon filter composed of high performance activated carbon and chlorine, odor,organic contaminants,pesticides and chemicals that affect the taste from the smell, it purifies. In 1 year a change is made.