This is the FEZ Spider compatible serial-USB module. Using this module, any of the serial UART sockets on mainboard can be converted into a virtual serial connection over USB. Use this connection to transfer data to a PC or for debugging over serial (virtual serial over USB). This is useful when needing to free up the USB client port for other purposes, like simulating a mouse or keyboard on USB Client port.
Works with any socket type U. Can also work with K sockets (serial + handshaking) with minor hardware changes. Note that K is purposely not marked on the module.
We sell the FEZ Spider Starter Kit here.