TDS Water Quality Test Pen: Professional TDS, EC and temperature pen. Upgraded to a large backlit LCD display for easier reading and an auto-lock feature for easier use TDS Meter Water Quality Tester: It has a hold function for recording measured values, which is convenient for reading and recording. Precise High-Precision Test Pen: TDS stands for Total Dissolved Solids, which are inorganic salts and organic matter in liquids. This includes calcium, magnesium, sodium, and more. LCD Display Water Quality Tester: With the push of a button, the TDS can tell you your overall water purity level, which will be displayed on the screen in PPM. Drinking Water Meter: For accuracy, it features a high-quality titanium alloy probe and reliable Automatic Temperature Compensation (ATC) to ensure consistent accurate readings in a wide range of temperatures. Package Quantity: 1 piece