The Bluelab? Soil pH Pen provides a pH and temperature reading of soils and media, so you know that the right nutrients will be made available to your plants. In soils or growing media, pH strongly influences the availability of the microorganisms to plants in the soil. Now you can closely monitor and adjust the pH levels right from the palm of your hand for optimum plant health and performance. It will also measure solutions too. Easy to use buttons with selectable units for ?C and ?F. Backlit LCD display with a low battery warning. It has a successful pH calibration indicator as well as hold and auto off functions.