Solaxx CLG20A Saltron Mini Drop-in Salt Chlorine Generator for Hot Tubs & Swim Spas Up to 2000-Gallons For Any Spa or Swim-Spas up to 2,000 Gallons Cell Polarity Auto Reverses to Prevent Scaling Helps Maintain Constant Sanitizer Level Programmable Digital Timer Mere 3,000 ppm Salt to Operate