<p>Sincereetali</p>The meter has been used for a long time since the last calibration or use. The meter has been used under particularly continuous conditions. Do not press the Temp/Cal button for a long time at ordinary times, otherwise the meter needs to be recalibrated. The water quality monitor is a professional and useful tool for testing the level of PH/EC/TEMP/TDS solution. It looks like a pen, which is perfect for carrying. Excellent for various uses, such as drinking water, aquariums, laboratories, water quality control, swimming pools and so on. Product Description Features: pH Range: 0.00 ~ 14.00 PH. EC: 0-1999 us/cm 0-19.99 ms/cm. TDS: 0-1999 ppm 0-19.99 ppt. Resolution Temperature: 0 to 50 °C. PH 0.01PH. EC: 1 us/cm (< 1999 us/cm), 10 us/cm (> 1999 us/cm), 0.01 ms/cm. TDS: 1 ppm (< 1999 ppm), 10 ppm (> 1999 ppm), 0.01 ppt. Temperature: 0.1 °C. pH Accuracy: ± 0.02 PH. EC: 2% FS TDS: 2% FS. Temperature: 0.5 °C. Automatic temperature compensation: 0 °C to 50 °C. Battery type: 3 × 1.5 V (AG13). Operating temperature: 0 °C to 50 °C. Calibration: Two points (4.01, 6.86) or one point (6.86) calibration. Automatic shutdown: after 8 minutes. Dimensions: 188 x 35 x 35 mm. Weight: 98 g.