Owl Communication Cards comprise the core technology of Owl data diode products. Each Communication Card Kit is comprised of two purpose-built network interface cards (one send, one receive) a fiber optic cable, and a specialized Transfer Software Application. Each individual card is installed on a separate host server in a PCI Express slot and they communicate in a single direction over a fiber optic cable via the asynchronous transfer mode (ATM) protocol. ATM serves two purposes – the first is to “break” the protocol of the original transfer for additional security, the second is to facilitate a high bandwidth, low latency one-way transfer using a protocol specifically designed for it. Each card is color-coded: Blue for send, and red for receive. The send card resides in a designated send server (blue) on the source network, and only has electronic components, including an LED, for transmitting information. The receive card resides in a designated receive server (red) on the destination network, and only has electronic components, including a photodetector, for receiving information. The hardware design of these cards physically enforces deterministic, one-way only data transfers.