By replacing just the resin in your CR Spotless Water System, you'll reduce waste and still maintain the same level of de-ionization. Simply unscrew the housings and remove the spent cartridges. Dispose of the used resin, rinse the cartridges and refill them with the new resin. Put the cartridges back inside the housings and reattach them to the main unit. It's quick, easy, and environmentally responsible. You will receive two CR Spotless Replacement Resin Bags that will de-ionize approximately 300 gallons of water. These bags are pre-measured for the DIC-20 High Output Rolling System and the DIW-20 Wall Mounted System.