This USB to UART Bridge is a module, base on Silicon Labs CP2104 UART bridge, and it is a good solution for connecting micro-controllers and other digital serial devices to PC. 
For connecting to PC used standart USB-A socket.
The device also features up to four GPIO signals that can be user-defined for status and control information. Direct access driver support is available through the Silicon Labs USBXpress driver set. See www.siliconlabs.com for the latest application notes and product support information for the CP2104.

This board uses 5V signal levels by default. For use 3.3V level, pls cut off the bridge for 5V of soldering pads on bottom side of board, and make soldering the pads for 3.3V
For get detail information of IC CP2104 USB-UART bridge, pls folow this link: http://www.silabs.com/products/interface/usb-bridges