It is a cost-effective and 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 TDS meter measures the concentration of dissolved solids and displays the result on the screen in parts per million (ppm). Lower TDS levels 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 wide range of applications, including drinking water assessment, water filtration and purification systems, hydroponics (nutrient testing), aquariums, RO/DI systems, swimming pools, spas, and various commercial and industrial uses. It features a durable, handheld design and comes with a protective carrying case. This portable TDS meter is widely used 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 results. Digital TDS meters are ideal for use in hydroponics, gardening, aquariums, reef tanks, water ionizers, and filter testing. Common applications include monitoring drinking water, water purifiers, carbon filters, hard water, tap water, refrigerator water filters, reverse osmosis systems, and hydraulic filtration. Measuring range: 0–9990 ppm, 1 ppm resolution, ±2% reading accuracy. Power supply: 2 x 1.5V (LR44 button battery), batteries not included. Color: Black Material: Plastic Size: 155 mm Package Contents: 1 x TDS Pen Note: Lighting and display differences may cause slight variations in the color shown in images compared to the actual product. Measurement error allowance is ±1–3 cm.