Tester with 4 Display ModesThis advanced water difficulty test combines TDS (Total Dissolved Solids), CE (Electrical Conductivity) and a 3 in 1 digital temperature measurement test pen. This pH meter has 4 display modes to choose from, TDS - ppm and C, EC - s/cm and C, TDS - ppm and F, EC - s/cm and F ( press the button MODE to convert). Luminous alarm functionLatch function makes it easy to read and record, press the HOLD button, then differentiate it from the test solution. PH tester has light alarm function, green backlight with TDS value less than 40; red backlight when the TDS value is over 40. Auto Power OffThe pH tester without operation 2 minutes automatic shutdown, so that the battery does not run out, a convenient function of Auto power off ensures long battery life. Wide ApplicationThis digital TDS tester provides detailed and accurate report on the quality of drinking or used water for your pets , your fish and your gardening. Multiple Accessories 1 * PH meter, 1 * protective case TDS, EC and temperature meter 3 in 1 EC: 0 to 9990 s/cm TDS: 0 to 9990 ppm (parts per million) Temperature range: 1-80C; 33 to 176F Accuracy: +/- 2% Notes: To make sure the reading of this digital TDS tester pen is correct, it is better to buy pure water or distilled water to test, because both waters have a fixed value of -0, but the pool/SPA water does not have a fixed value. If 0 ppm is still displayed during the tester, don't worry. Please follow the steps below. Please check if the chip is exposed as the picture, if yes, follow step 2. Open the battery cover , then press the battery. Please check whether the chip is reset as the pictures show. If the chip is in the correct position, you can test it in the water. Package Contents: 1 x Water Test Meter 1 x Protective Leather Case Note:< /p> Do not drop the TDS meter assembly into water or immerse beyond the maximum immersion level. This tester pen is not a waterproof design. come out of exhalation. Please rinse the probe with pure water after use, otherwise it will affect the accuracy of the next use (please avoid getting the pen body wet). < p>Do not store the TDS meter at high temperatures or in direct sunlight. Please avoid collisions, weights or dropping. If the reading is 0 ppm, try pushing the battery to