The Aquatic Life DI Color-Changing Mixed Bed Resin Cartridge is designed exclusively for use with the RO Buddie 3-Stage Reverse Osmosis System. It contains a high quality resin mixture for direct water purification. The residuals produce average conductivity values of approximately 0.1µS/cm for the majority of the service run. For added convenience, the resin changes color (from green to blue or blue to brown) to indicate exactly when it's time for replacement. The cartridge is also refillable to enable easy customization of your water treatment. Press-fit connections on either side of the cartridge attach easily to 1/4" tubing (sold separately). Includes clips for mounting to RO Buddie. 2.5" dia. x 12.25"