General description A very complete 4-in-1 pH tester kit designed to check the quality of water for various applications, including drinking water, aquariums, hydroponics, and swimming pools. This compact and lightweight device resembles a pen, making it easy to handle and use. Technical specifications pH measurement range: 0.00 to 14.00 TDS measurement range: 0 to 19,990 ppm Installation No tools are needed for calibration; simply immerse the pH meter electrode in the solution. Usage Press "ON/OFF" to turn on the electronic pH meter. Shake gently and wait a few seconds for the readings to stabilize. The device features a "HOLD" button to freeze the measurement result for easy reading. Automatically calibrates to three points (6.86 and 4.01 point calibration).