The HI991300 is a slim, lightweight, and waterproof portable meter that measures pH, conductivity (EC), total dissolved solids (TDS) and temperature with a single amplified probe. The meter operation is simplified with two buttons. One is used for on/off and for calibration while the other is used to switch between the measurement modes. The HI991300 has advanced features including a selectable EC to TDS conversion factor (0.45 - 450 ppm and 1.0 - 1000 ppm).