Sun Port&reg; 3-in-1 Soil Moisture Meter with Plant Light & PH Test Gauge Function, Suitable for Testing pH Acidity, Moisture & Sunlight for Gardening, Farming, indoor & outdoor (JC-PH-Meter) This device measures soil's moisture pH and light by just plugging in the probe It let you know when to water, how to control PH level, and determine if plant is getting adequate light With scientifically accurate moisture, ph and light level data, you can promote the health of your plants easily This device requires no battery nor external power supply. It is simple to use, and has long life-span