WINGONEER&reg; 5pcs Soil Hygrometer Humidity Detection Water Sensor Module YL-69 Sensor and HC-38 Module for Arduino This is a simple water sensor that can be used to detect soil moisture. Can be used in module plant waterer device, and the plants in your garden no need people to manage. This is a must have tool for a connected garden! It will be helpful to remind you to water your indoor plants or to monitor the soil moisture in your garden. Operating voltage: 3.3V-5V Module dual output mode, digital output, analog output more accurate.