The Bluelab Combo Meter is a conductivity, pH, and temperature meter all in one. It comes with a pH probe and conductivity and temperature probe. Just place it into the solution and the selected reading is displayed on screen. The Bluelab Combo Meter is portable and does not require a power supply. Calibration of the pH is very easy using the push buttons on the meter and fresh Bluelab calibration solutions. Conductivity and temperature do not need to be calibrated as they are locked in during manufacture. Select display options for temperature (C or F), and EC, CF, TDS, or ppm (700).