The World's Most Simple, Accurate, Rugged and Reliable Rain Sensors. There’s nothing more embarrassing – or more wasteful or costly – than an irrigation system that runs when it doesn’t have to…in the rain. And the simplest, most effective way to prevent your sprinklers from coming on during or after precipitation is the Hunter Mini-Clik®. Easily installed on any automatic irrigation system, Mini-Clik® shuts sprinklers off in a storm and keeps them off, automatically compensating for the amount of rainfall that occurred. Disks absorb water and then expand proportionally to the amount of rain that fell (e.g., a small cloudburst would result in little absorption, a thunderstorm with 6" of rain would lead to more absorption and thus more expansion). As the moisture-laden disks expand, they eventually activate a switch that interrupts the circuit from the controller to the solenoid valves. Once dry, they contract and release the switch. Thus, the Mini-Clik® automatically resets without ever affecting your controller. Built to withstand the harshest conditions, there’s no better way to ensure that your system isn’t watering when it isn’t necessary…no wonder the Mini-Clik® name has been synonymous with rain sensors for more than two decades.