This is a USB to TTL serial cable, with a FTDI FT232RL usb/serial chip embedded in the head. It has a 6-pin socket at the end with 5V power and ground, as well as RX, TX, RTS and CTS at 3V logic levels. These are perfect for use with a Boarduino, Meggy's, or other Arduino clones and derivatives, and Fuzeboxen. Useful whenever you want to communicate with a TTL serial device, such as an XBee. Now it's easier than ever to debug your setup or see data transfer, the red and green LEDs will blink when data is transmitted/received by the FTDI chip. The data signals are at 3V and the power line provides 5V. Because the cable is 5V-logic compliant, you can use it with 3v or 5v logic just fine - no level shifting required!