The Rain Sensor avoids unnecessary wastage of water by simply shutting down the water timer when it rains. A smart, efficient way to save water especially where watering restrictions are in place. When rain water on the ground is 15.7 ounces by square feet, the Rain Sensor internal float lifts so that a signal is sent to the water timer to stop all programs after the one in current operation. Once rain water has evaporated, the timer programs are automatically resumed even when evaporation happens during a programmed watering cycle. Extremely easy to install, remove the jumper from inside the water timer and insert the 6 foot Sensor cable (additional cable of same or larger diameter can be added to a maximum of 65 feet). Supplied with a stainless wall bracket and screws, it should be mounted in a clear area that has no coverage of plant life, foliage and undergrowth. Unit is 100% quality controlled during manufacturing process. 2-year warranty. Made in Italy. Should not be exposed at temperature below 37.4°F or higher than 122°F.