Digital TDS Meter Tester: Test water quality purity. Check the performance of your water filter, Make sure you always drink pure water! How to Use: 1. Remove the protective cap. 2. Turn the TDS Meter on. 3. Immersing the meter into the water or solution up to the maximum immersion level. The height of the solution should not exceed 4cm(from the pen point). 4. Waiting for the reading to be stable. The measurement values of the TDS meter were influenced by temperature much. So it needs time to correct the readings. 5. The value of TDS will be fixed on the display between 10-30 seconds. Hold down the" hold" key to lock the value. 6. Wiping the remaining water from the pen with a tissue after you usage and re-cover the pen cap. Please Note!! - Please avoid striking, press weighty and fall off. - Please don't store the TDS under the high temperament direct sunlight. - Please don't drop the entire TDS meter in the water or dip beyond the maximum immersion level. Specifications: Accuracy : +/-2%. Rang :0-9990ppm. Battery: 2 x 1.5V button cell. Item Size :155mm x 28mm x 15mm. Package Included:1 x TDS Meter Tester.