It is a convenient digital tool that can instantly check overall water quality. TDS stands for Total Dissolved Solids, which refers to any salts, metals, or minerals present in water. With the press of a button, the TDS meter displays water quality readings on screen in ppm (parts per million). Lower TDS levels indicate purer water, with pure water measuring 0 ppm. This meter is suitable for testing tap water quality and determining when to replace water filters. (Note: The meter does not detect biological contaminants.) Ideal for use in drinking water assessment, water filtration and purification systems, hydroponics (nutrient testing), aquariums, RO/DI systems, swimming pools, spas, and various commercial and industrial applications. The device features a rugged, durable design and includes a protective carrying case. This handheld TDS meter is designed for reliable performance in industrial and commercial environments. The meter includes a carrying case with belt clip functionality. Advanced microprocessor technology and a built-in digital thermometer ensure accurate and efficient measurement data storage for easy reading and recording. Features a clear, easy-to-read LCD display. Perfect for testing in hydroponic systems, swimming pools, spas, aquariums, reef tanks, water ionizers, and general water quality monitoring. Suitable for testing drinking water, water purifiers, carbon filters, spring water, hard water, tap water, refrigerator water filters, reverse osmosis systems, and other water treatment applications. Measuring range: 0–9990 ppm Resolution: 1 ppm Accuracy: ±2% of reading Power supply: 2 x 1.5V (LR44 button battery), not included Color: Black Material: Plastic Size: 155 mm Package Contents: 1 x TDS Pen (Only the above items included; others not included) Note: Lighting and display differences may cause slight color variation between the image and the actual product. Measurement error allowance: ±1–3 cm.