Rain Bird® ESP Modular Controllers Designed with your growing landscape needs in mind, the ESP Modular controller is flexible, simple to use and Rain Bird® reliable. Modular stations allow you to flexibly add more irrigation zones as your landscape grows. Easily upgrade with 3-station modules up to 13 stations. Unique Auxiliary Station™ allows you to water even when rain has temporarily suspended the controller from watering. Ideal for watering under covered patios, operating landscape lighting, fountains or other non-irrigation systems.