This economical waterproof (IP-67 rated case) instruments offer pH, conductivity, TDS (Total Dissolved Solids) and temperature readings in one easy to use meter. Features include automatic calibration, automatic temperature compensation (ATC), selectable Conductivity/TDS conversion factor, adjustable conductivity temperature coefficient, stability indicator, battery error prevention system and battery strength percentage gauge. All functions are accomplished with only two buttons. Two conductivity ranges are available: 0 to 3999 µS/cm (HI 991300) or 0.00 to 19.99 Ms/cm (HI 991301). Each meter is supplied with pH/EC/TDS/°C probe with one meter cable & batteries in a hard carrying case.