The COM-300 is an advanced waterproof combo meter with superior accuracy.The meter measures four parameters: pH, electrical conductivity (EC), total dissolved solids (TDS) and temperature.Features include 2 different conductivity conversion factors to convert EC to TDS using the 0.5 (NaCl) or 0.7 (442TM), as well as selectable modes for measurements in the S, mS and ppm scales.The meter incorporates automatic temperature compensation (ATC) to accommodate for discrepancies in temperature that would naturally occur and also features digital calibration for easy and precise calibration that will yield better results.