Features: Measures PH, TDS, TEMP, EC, Salinity, SG, ORP. Calibration Conductivity EC: Supports 3-point calibration automatic recognition (1413us 12.88ms and 111.8ms) by 3 calibration points (1413uS/cm 12.88mS/CM 111.8mS/CM) pH: 1 point (6.86) or 2 points (6.86 4.00) (6.86 9.18) or 3 points (6.86 4.00 9.18) can automatically recognize the calibration solution Waterproof rating: IP67 Lightweight and stylish design Large LCD display Display supports backlight Automatic temperature compensation (ATC) Data hold function and low battery indicator Power consumption 2.9 mA, power consumption 0 The accuracy within 150ppt is relatively accurate, and the deviation above 160ppt is large. Auto power off: 5 minutes Specifications: EC measurement range: 0 to 10000uS/cm 10.01-19.99ms 20.1-400mS/CM Resolution: 1 uS/cm; 0.1ms/cm; Accuracy: 2% of reading TDS measurement range: 0 to 1000ppm 1000ppm to 10000ppm 10.1 to 200.0ppt Resolution: 1ppm; 0.1 point Accuracy: 2% of reading Salinity measurement range: 0.00 to 25.00% Resolution: 0.01% Accuracy: 0.01-5.00% (0.1%) 5.10-25.00% (1%) PH measurement range: 0.01-14.00pH Resolution: 0.01pH Accuracy: 0.05pH ORP measurement range: 0?999mV SG: Measurement range: 1.000?1.222 Working environment: 0 to 60.0C (32.0-140F); relative humidity 100% TDS coefficient: 0.4 to 1.0 Temperature range: 0.1-60.0C 32.0-140F Temperature accuracy: 0.5C Temperature resolution: 0.1C/F Power supply: 3x1.5LR44 (not included) Display size: 33*24mm