Now you can SAVE MONEY buying resin in bulk and reusing the plastic cartridges that come with the system. This item has 6 bags of resin, replacing your unit 3 times. The resin replacement bags 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, rinse cartridge, and refill with new resin. Then, put the cartridges back inside the housings and reattach it to the body of the unit. It's EASY! The bulk bagged resin will recharge your DIC/DIW 20 3 times.