DI Resin is necessary to reduce Total Dissolved Solids (TDS) to zero and is the last stage of an RO/DI unit. It is unnecessary to use the expensive proprietary DI cartridges that other RO manufacturers sell. Simply buy a refillable DI cartridge if you don't have one already and fill with DI resin. You'll save money and get the same results.

Color Changing DI Resin Refill
• Fills 1 standard 10" refillable cartridge
• Changes color when exhausted
• Vacuum packed in foil lined 4mm Mylar bags to preserve quality (see below for more info)
• 2 year shelf life