Mobile Spot Free Replacement Resin for units 20" Big Blue and CR Spotless 120 single housing. The packet holds 0.145 cubic feet / 6.4 pounds / 2.9 kilograms in a sealed bag of Mixed Bed Resin The Resin is designed to treat potable water to 500,000 ohms or better quality of spotless water. Specifications for this product are included in the picture section of this listing.