Shapure TDS Meter Total Dissolved Solids, also known as TDS, are inorganic compounds that are found in water such as salts, heavy metals, and some traces of organic compounds that are dissolved in water. How to Use TDS Meter? Remove the protective capTurn the TDS meter ONImmerse the meter into the water up to the maximum immersion levelLightly stir the meter to dislodge any air bubbles and wait for the display to stabilizePress the hold button to view the reading out of the waterTurn off the meter, wipe and dry the electrode off before inserting it back into the protective cover Specification: Range: 0~9990 ppm Temperatures：32~212℉ Accuracy: ±2% full scale Power Source: 2 x 1.5V (button cell) Weight: 56g Dimensions: 6.2 x 1.2 x 0.8 in. Product Feature: High Accuracy Titanium Alloy.Automatic Temperature Compensation: 0 ~60.Working temperature: 0 ~50.Hold function: Saves measurements for convenient reading and recording.Auto-function: Turns off meter after 10 minutes of non-use to conserve batteries.Measurement ranges from 0-9990 ppm.This water meter can be also used in testing water purifiers and filters, food (vegetable, fruits) & drink quality monitoring, pools, spas, aquariums, and hydroponics.