This product has a five-in-one function, which can measure ph, tds, ec, salinometer and temperature Measurable salinity (sea salt/freshwater salt) Sea Salt: Seawater salinity is the ratio of total dissolved solids to the weight of sea salt in seawater, usually expressed in grams per kilogram of seawater. (Measuring range 10.1-200.0ppt) Light salt: light water with salt content less than 0.5g/L (measurement range: 0.00-25.00% accuracy: 0.01-5.00% 5.10-25.00%) Waterproof grade: TP67 (it can still be used after falling into the fish tank) replaceable probe Auto Calibration Product Description Product parameters Conductivity test range: 0 to10000uS/cm 10.01-19.99ms 20.1-400mS/CM Resolution: 1uS/cm; 0.1mS/CM Accuracy: 2% of reading Tds test range: 0 to 1000ppm 1000ppm to 10000ppm 10.1 to 200.0ppt Resolution: 1ppm;; 0.1ppt 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 test range: 0.01-14.00pH Resolution: 0.01pH Accuracy: 0.05pH Temperature Compensation: Automatic Temperature Compensation (ATC) Working environment: 0 to 60.0C (32.0-140F); RH 100% TDS factor: 0.4to 1.0 Temperature range: 0.1-60.0 32.0-140 Temperature accuracy: 0.5 Temperature resolution: 0.1C/F Auto power off: about 5 minutes 3x1.5LR44 Display: Support backlight Waterproof grade: IP67 Power consumption: 2.9 mA, power consumption is 0 when off The accuracy is relatively accurate within 150ppt, and the deviation above 160ppt is relatively large. Note: After each use, be sure to clean the electrode