|The Extech WQ510 measures pH, ORP, and Temperature. It features a built-in Stirrer with 30-, 60-, and 120-minute timer or continuous mode, 2- or 3-point pH calibration, Automatic Temperature Compensation, large backlit dual display, and manual store/recall (150 readings). Capture readings directly to a PC via built-in USB interface. The WQ-510 adds Conductivity, TDS, and Salinity measurement. Features also include 1-point Conductivity calibration, Adjustable Conductivity to TDS Ratio, and Manual Salinity compensation.