This product has been discontinued by the manufacturer. Please contact us for the closest replacement - Chlorine, cyanuric acid and pH photometer: Range Free Chlorine: 0.00 to 5.00 mg/L; Total Chlorine: 0.00 to 5.00 mg/L (ppm); Cyanuric Acid: 0 to 80 mg/L (ppm); pH: 6.5 to 8.5 pH