Additional Red Expander Boards forPdkâ€â„s Redâ„ Max controller. Pdkâ€â„s Redâ„ Max controller is truly in a class of its own, coming fully equipped with two Altronix power supplies and two Red four-door expander boards. The Red Max is fully customizable with any Red expansion board, allowing for scalability and control of up to 24 doors from one enclosure. Expander boards are available in one-door, two-door, and four-door options. Each expander includes built-in Ethernet connectivity and self- discovery, simplifying IP configuration and functionality. Red 4 Expander Connections Removable Screw-down Terminals Industrial-grade 2A Form-C Relays (4) Reader (4) Input A (4) Input B (4) General Information Name: PDK R4E Red 4 Four-Door Expansion Board, ProdataKey, LLC, ProdataKey Category: ProdataKey, Access Control, Control Panels, Control Panel Boards UPC Code: 850038472054 Country of Origin: United States. Country of origin is subject to change.