Operating voltage:3.3V~5V Dual output mode,analog output more accurate. * Panel PCB Dimension: 30mm * 16mm Soil Probe Dimension:60mm*30mm * Interface Description (4-wire) VCC: 3.3v-5v GND: GND * DO: Digital output interface (0 and 1) AO: Analog output interface * Soil moisture module is most sensitive to the ambient humidity is generally used to detect the moisture content of the soil.