It is a convenient digital tool designed to quickly assess overall water quality. TDS refers to Total Dissolved Solids, which includes salts, metals, and minerals present in water. With the push of a button, the meter measures TDS levels and displays the result on the screen in parts per million (ppm). Lower TDS values indicate purer water, with pure water registering 0 ppm. This device is ideal for testing tap water quality and determining when to replace water filters. (Note: The meter does not detect biological contaminants.) The TDS meter is suitable for a variety of applications, including drinking water assessment, water filtration and purification systems, hydroponics (nutrient testing), aquariums, RO/DI systems, swimming pools, spas, and general industrial uses. It features a rugged, durable design and comes with a protective carrying case. This handheld TDS meter is designed for reliable performance in both residential and commercial settings. Included is a carrying case with a belt clip. Advanced microprocessor technology and a built-in digital thermometer ensure accurate and efficient measurement readings. The device features an easy-to-read LCD screen for clear display of results. Digital TDS meters are ideal for use in hydroponics and gardening, pool and spa maintenance, aquarium and reef tank monitoring, water ionizers, and various water filtration systems. Applications include testing drinking water, water purifiers, carbon filters, hard water, standard tap water, refrigerator water filters, reverse osmosis systems, and other filtration setups. Measuring range: 0–9990 ppm, 1 ppm resolution, ±2% reading accuracy. Power supply: 2 x 1.5V (LR44 button battery), battery not included. Color: Black Material: Plastic Size: 155mm Package Contents: 1 x TDS Pen Only the items listed above are included; other accessories are not included. Note: Lighting and display differences may cause slight variations between the color shown in the image and the actual product. Measurement error allowance is ±1–3cm.