The PCC 12 station indoor controller, also known as the PCC1200i is a fixed version of the Pro-C modular controller. This model consists of 12 stations and cannot be expanded with the use of additional expansion modules. Sprinkler Warehouse does sell the base modular version of the controller which includes a 4 station module and can be expanded with the use of the PCM-300 and PCM-900 expansion modules.