Rain Bird ESP-Me Smart Controller LNK WiFi 4 Station Modular. With 4- to 22-station scalability, the ESP-Me helps you better serve your customers. Install the same controller on residential and light commercial sites - the more stations you add, the more you save, providing you and your customers with more value for the money. Best of all, you can upgrade existing ESP-Me installations by simply installing a new Wi-Fi-compatible front panel and LNK Wi-Fi Module, without having to replace the entire unit.