The Bluelab� pH Probe Care Kit is everything you need to maintain cleaning and correctly store your pH probes to ensure you get the most accurate readings possible. The Bluelab� pH Probe Care Kit will maximise the life of a probe. pH probes specifically, should be kept wet at all times for optimal performance and life. The probe surface is where the instrument takes the reading of the solution or soil/media. If the probe face is dirty or contaminated, the readings may be inaccurate. Much like the windshield of a car, if it�s dirty you can�t see out! If the probe face is dirty, it cannot read the solution or soil accurately.