This package includes a Sensor of Level of Water and a Sensor of Humidity from Solo. If the plates have water covering the sensor components, an analog value will be available on the "SIG" connection. The Sensor of Level of Water can detect up to 4cm of water. This way, you can check if your aquarium, or your pet's water bowl, still has enough water. You can use the Sensor of Moisture of the Soil to check your plant's soil or growing environment, for example.