This is a digital TDS EC tester to test the filter water quality purity, to check the performance of your water filter, to check for hardness (1grain=17ppm), and to make sure you always drink pure water. Features of the TDS & EC Temp Meter Hold Function Auto-off Function (After 10 min.) Built-in digital thermometer Includes a carrying case with a belt clip Factory calibrated with a 342 ppm NaCl solution. (The meter can be recalibrated with a mini-screwdriver). Specification of 3 in 1 Meter Digital TDS EC TDS Range: 0 – 9990 ppm (mg/L) Range: 0 – 80 degrees Celsius Resolution: 0-999: 1 ppm; 1000-9990: 10 ppm (indicated by an ‘x10’ icon) Temperature Resolution: 0.1 degree Celsius (Celsius only) Accuracy: /- 2% EC-to-TDS Conversion Factor: NaCl (avg. 0.5) ATC: Built-in sensor for Automatic Temperature Compensation of 1 to 50 degrees Celsius (33 to 122 degrees Fahrenheit) Power source: 2 x 1.5V button cell batteries (included) (LR44 or equivalent) Battery life: 1000 hours of usage Dimensions: 15.5 x 3.1 x 2.3cm (6.1 x 1.25 x 1 inches) Weight with case: 76.5g (2.7 oz) Weight without case: 56.7g (2 oz) Country of Origin: China Supplier & Reseller: Labtex Bangladesh.