The TRM-1 is a wide-range TDS monitor, able to measure 0 to 10,000 ppm with three different sensors. It is ideal for water filtration/purification systems that require three sensing points, such as RO/DI systems. Each sensor is ¼ in. in diameter. The monitor comes with three ¼-in. quick-connect T-fittings. It is battery powered, has automatic shutoff, automatic temperature compensation and an accuracy of ±2% (of the reading).