The EcoSense EC30A Conductivity/TDS/Temperature Pen is a pen-style conductivity, total dissolved solids (TDS), and temperature tester with automatic temperature compensation, one- or two-point calibration, graphic LCD screen with onscreen instructions, and manual or auto-ranging for conductivity or TDS. It has a user-replaceable electrode, an electrode cap, a belt clip, and an IP67-rated waterproof case. The memory can store 50 data sets. 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. SpecificationsSpecifications Conductivity range 0.0μS to 19.90mS Conductivity resolution 0 to 1990 μS/cm, 5 μS/cm, 2.00 to 19.90 mS/cm, 0.05 mS/cm Conductivity accuracy + or - 1% Full Scale TDS range 0 mg/L to 10.00 g/L TDS resolution 0 to 1000 mg/L, 5 mg/L, 1.00 to 10.00 g/L, 0.05 g/L TDS accuracy + or - 1% Full Scale Temperature range 0.0 to 99.5 degrees C (32.0 to 212.0 degrees F) Power source Four LR44 alkaline batteries Data management features 50 data-set memory Weight (with batteries) 105g (3.7 ounces) 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. YSI manufactures instruments, sensors, and software for environmental water quality monitoring and testing. The company, founded in 1948 and headquartered in Yellow Springs, Ohio, meets International Organization for Standardization (ISO) 9001 standards.What’s in the Box?EC30A instrument606114 electrode(4) LR44 alkaline batteriesInstructions