... 1.filter cartridge,filter core,water filter cartridge,CTO 2.20" CTO cartridge,can be made of normal carbon, or coco nut carbon The carbon filter cartridge ... form the water, according to the requirements, various types and size are available for option.Length: 5.10.20inchCTO cartridge ... , can be made of normal carbon, or coco nut carbon, has different color, you ...