1、Suitable for tap water, drinking water, fish tank water and other water systems. 2、For easy reading and recording, the instrument will hold the reading. 3、Automatically close after 10 minutes in case of forgetting to turn off the computer. 4、Highly efficient and accurate due to its imported chips. 5、Lightweight and portable design, convenient for indoor and outdoor use. Features: Suitable for tap water, drinking water, fish tank water and other water systems. For easy reading and recording, the instrument will hold the reading. Automatically close after 10 minutes in case of forgetting to turn off the computer. Highly efficient and accurate due to its imported chips. Lightweight and portable design, convenient for indoor and outdoor use. Specification: Material: ABS + Plastic casing Measuring range: 0-9999ppm (when the measured value exceeds 9999, the display value is X10) Accuracy: ±2% Battery: 3V *1 (button battery, not included) Size: 149 * 26 * 15mm / 5.9 * 1.0 * 0.6in Weight: 60g / 2.1oz Package list: 1 * Water Quality Tester 1 * User Manual Instructions for use: 1. Take off the pen holder and turn on the switch. 2. Put the pen into the solution to be tested, the height of the solution should not exceed 4cm. 3. Gently stir the pen in the solution to be tested. After the value is stable, the measured value of TDS is greatly affected by the temperature. Therefore, the temperature compensation is used to correct the reading. The TDS number will be fixed on the display within 10-30 seconds. Above, in order to lock the reading, press the hold button. 4. After use, wipe the water in the tip of the pen with a cloth and cover the pen holder. Notes: 1. Please avoid the TDS test pen soaking in the water. 2. Please avoid high temperature, direct light. 3. Please avoid impact, heavy pressure or fall.