To operate the Enhanced Presence Sensors (#790901), you'll need a processor board. This 3 Zone Processor Board analyzes the floor flexing and responds by activating a corresponding normally open or normally closed Form "C" relay. The processor consists of a printed circuit board and will need an enclosure for protection and a 12VDC power supply (each sold separately). This board can accomodate up to 12 Enhanced Presence Sensors. We also offer a smaller processor board (#790911)that accomodates 4.