If you need to replace the plastic resin housing and want the resin already pre-packaged, then the RC2-10 and RC2-20 are for you. These pre-packed columns of resin simply drop back into your CR Spotless housing and don't require any measuring. The resin replacement columns are easy to install and virtually hassle free. You can change the resin in less than 5 minutes. Simply unscrew the watertight housings and remove the spent cartridge. Properly dispose the used resin, then put the cartridges back inside the housings and re-attach it to the body of the unit. It's EASY! The RC2-10 is for the DIC/DIW 10 and the RC2-20 is for the DIC/DIW 20. These cartridges will recharge your DIC/DIW 10/20 1 time.