Features - The digital pH pen is equipped with automatic temperature compensation. The TDS meter has a locking and auto-off function (please note: this meter cannot test sea water.) At the push of a button, it can display data on the water purity level in PPM (parts per million) on the screen. Soil meters can test soil pH and help you control the pH level in your soil. (Note: This tester is for soil testing only.) Accurate and Reliable - These testers provide fast and accurate testing in the 0.01 pH range. Accurate and stable readings are displayed in seconds and the results appear on the screen. EASY TO USE - pH testers and TDS meters have sensitive electrode sensors, just press "on". Results are displayed on the screen in just a few seconds. The soil test kit simply inserts the probe into about 4-6 inches (about 10.2-15.2 cm) of soil and waits about 10 seconds for visual data to be read. No battery required. Wide range of applications - These meters are designed to be compact and convenient. PH meters and TD&EC meters can test pH balance, ideal for testing drinking water, swimming pools, aquariums, spas, hydroponics, food, and more. The soil tester is suitable for plants, gardens, lawns and farms such as rice/vegetables/flowers etc.