Product Information:The three station module for ESPControllers easily upgrades a 4station base model to 13 stations with the addition of this 3station hotswappable module at installation or in the future, which can be added without powering down the controller. The unit can be installed in any available slot. Its 5year lithium battery and nonvolatile memory keep dates, times, and program schedules up to date even with interruptions like a power outage. Its surge protection is unbeatable, withstanding nearly 3 times higher electrical surges than competitive controllers.The module is also fuseless and uses a state of the art diagnostic circuit breaker to identify a station with valve or wiring problems while continuing to water operable stations. It expands easily from a 4 station base to 13 stations when you add other 3station modules.A 365day calendar functions with leapyear intelligence so that any schedule you set will stay set, worry free, for years. The module also features four irrigation cycle modes: Custom 7day calendar; cyclic 131 day interval; and odd/even day calendar.)A Contractor Default System makes it easy for you to access your default program, even if it has been overriden by a homeowner. But the module is easy for your customers or homeowners to program themselves, as well. Rainbirds Extra Simple Programming style with larger LCD display allows the user to set time, date, and schedule. Global Season Adjust also offers the user the ability to readjust the valves in every program with the push of a button. Features:#149; Easy to install#149; Works with either indoor or outdoor ESP4M Controller#149; Adds three stations to controller Specifications:#149; Model: ESPSM3#149; Product number: F38200#149; Base controller sold separately