This listing is for 2 bags of 3.5lb special DI Resin for broutech spot free car wash system. (works with either single or Dual cylinder system). Each order will be 7lb and is good for one complete refill of the 20" DI Cartridge. Each Refill will be good for up to 400 gallons of water. The Broutech DI10 resin is designed to remove all the water spot for multiple industries, from car wash to solar panel cleaning the Broutech DI10 is a solution that will do it all for you. Each set of Resin will remove spot for between 300 to 400 gallons of water (depends on water source quality). Note: It is normal that this resin may contain water vapor and its color may vary due to humidity.