The Oakton WD-35634-46 pHTestr 5F pocket-sized pH tester with flat surface probe has a replaceable single-junction sensor which can be easily switched out, allowing you to save money by using the tester body over and over again. A large LCD makes viewing measurements easy and features a three-color backlight indicating operational mode - blue for measurement, green for calibration and red for alarm condition.

Additional features include a hold function to lock in measurements, self-diagnostic error message, and status icons for measurement stability, low battery voltage, and a flat probe that is ideal for surface or micro-volume testing. The IP67-rated housing features an easy-to-grip design and floats if accidentally dropped in water when sensor cap is on. Powered by 4 AAA batteries, the testers can operate up to 400 hours continuously. To conserve power, the unit will auto power-off after 8 minutes of non-use.

The pH testers feature up to 3-point pH calibration with NIST or US auto buffer recognition, a pH range from -2 to 16 with an accuracy of ±0.01 pH, and automatic temperature compensation. All three models can support a ORP probe (sold separately).