The Bluelab® pH Pen accurately measures both the pH and temperature in hydroponic systems. It's fully waterproof and also features a backlit LCD with the option to display in Celsius and Fahrenheit, double-junction probe, successful calibration indicator, hold function, low-battery warning, auto-off function and automatic temperature compensation. This pH pen has a range of 0.0 to 14.0 pH, with an accuracy of ± 0.1 pH, and 0 C to 50 C or 32 F to 122 F.
