Hydrologic Moisture Sensor. Save water with a fully automated watering system, Our Hydrologic Moisture sensor works with any of our Hydrologic timers. This unit senses the water content of the soil (you can adjust sensitivity) and sends a signal to your timer to shut off. Why let your timer water if it's raining out. Unit comes with a 16ft cord to reach your timer. Large, easy to use control dial to adjust senitivity. 8.93 inches high. Limited 7 yr warranty. Gray.