The GARDENA Soil Moisture Sensor works in conjunction with GARDENA water computers. When the soil has reached the desired moisture level, your automatic irrigation system will not be started, or an ongoing irrigation will be interrupted in this way you can save water and still have beautiful and healthy plants. Extremely water efficient since it only allows irrigation when necessary. It will function reliably for approximately one year using two 1.5 V alkaline batteries (not included) and a low battery level indicator will notify that it is time to change it. It comes with a two year warranty.