Hanna Instruments HI 98309 Ultra Pure Water is a factory calibrated water-purity tester designed for applications that use distilled, demineralized, or pure water, such as steam cleaning or car battery water maintenance; and measures in thousandths of microsiemens. The probe is replaceable and has graphite sensors for reduced polarization and has an automatic shutoff for low battery to prevent erroneous readings. Conductivity meters are commonly used in the water-quality testing, waste-water treatment, hydroponics, agriculture, and aquaculture industries, in cosmetics manufacturing, and in laboratory research. Specifications Range 0.000 to 1.999 μS/cm Resolution 0.001 μS/cm Accuracy + or - 2% Full Scale Calibration Factory calibrated Power source Four 1.5V batteries Dimensions 175 x 41 x 23mm / 6.9 x 1.6 x 0.9 inches (H x W x D)Weight 95g / 3.4 oz H is height, the vertical distance from lowest to highest point; W is width, the horizontal distance from left to right; D is depth, the horizontal distance from front to back. Conductivity meters, also known as electrical conductivity (EC) meters, measure the ability of a solution or material to conduct an electrical current. This measurement helps determine if the solution is, for example, contaminated or contains too much saline. In general, pure solutions, such as distilled water, have low conductivity. More saline- or nutrient-rich solutions, such as seawater or fertilizers, have high conductivity. Conductivity measurements are often used with total dissolved solids (TDS) measurements, which are typically expressed in ppm (parts per million). TDS consist of dissolved minerals and salts. To determine the amount of TDS, conductivity is measured, and the result is converted to a TDS measurement. Different meters provide results for conductivity, TDS, or both, and the application determines meter selection. Conductivity meters are used in research laboratories and a variety of industries, such as water-quality testing, waste-water treatment, hydroponics, agriculture, aquaculture, and cosmetics manufacturing.s Hanna Instruments manufactures analytical instrumentation and supplies, including pH meters, electrodes, chemical reagents, and buffer solutions. The company, founded in 1978 and headquartered in Woonsocket, RI, meets International Organization for Standardization (ISO) standard 9001. What’s in the Box?HI 98309 (UPW) meter Protective cap(4) 1.5V batteries Instructions