describe: EZ-9909 is a multifunctional pen which can measure ph pH value, tds solubility, ec conductivity, salinity and temperature. It is a high performance pen-shaped design and a waterproof water quality test pen for quick value measurement. The calculation result is stable and accurate. Waterproof level: TP67 (it can still be used after dropping into the aquarium) replaceable probe automatic calibration Specification: Conductivity test range: 0-10,000 uS/cm 10.01-19.99 ms 20, 1-400mS/CM Resolution: 1uS/cm; 0.1 mS/cm Accuracy: 2% of reading Tds test range: 0 to 1,000 ppm 1,000 ppm to 10,000 ppm 10.1 to 200 .0ppt Resolution: 1ppm; 0.1 ppt 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%) Range of pH Test: 0.01-14.00 pH Resolution: 0.01 pH Accuracy: 0.05 pH Temperature Compensation: Automatic Temperature Compensation (ATC) Operating environment: 0 to 60.0C (32.0 to 140F); 100% RH TDS Factor: 0.4-1.0 Temperature Range: 0.1-60.0C 32.0-140F Temperature accuracy: 0.5C Temperature resolution: 0.1C / F Auto shut-off: 5 minutes Batteries: 3x1.5LR44 (not included) Display size: 33*24mm Dimensions and weight: 183*37*37mm (7.2*1.5*1.5in) /90g (3.2oz) Please check the model and size before purchasing. If you have any questions about the product, please contact us contact.