Bluelab Soil pH PenSpecially developed for hobby and small scale growers, the Bluelab Soil pH Pen will help manage the success of your crops. Provides an accurate pH and temperature reading of soils and growing media, so you ll know that your plants are getting the nutrients they need. Features: Successful calibration indicator Measures soils and media Completely waterproof Backlit LCD display AAA alkaline battery included Warranty: 1 year repair or replacement