Orbit Rain Sensor is adjustable to 1/8", 1/4", 1/2", 3/4", 1" rainfall settings. Hygroscopic discs absorb water to activate rain switch. For use with all types of 24 Volt controllers. 30 feet of connection wire included. Easy one-step rain gutter mount bracket or can be mounted direct to flat surfaces. Adjustable vent provides fast or slow disc dry-out, adjustable to your climate. 7 Year Orbit Warranty. Normally closed, but can be changed to normally open. Rain Sensor Manual