I have just received two identical or similar boards. You sure can use them to program an Arduino Pro. Connect it as usually:Arduino / ConverterGND <-> GNDRX <-> RXTX <-> TXVCC <-> 5V or 3.3V depending on your Arduino Pro Version (or don't connect if you have separate power for your circuit)When programming from Arduino IDE, press and hold the Reset button during compilation and release it after information about sketch size appears and state changes to "Uploading". Uploading should begin and succeed.In case of problems - connect RX to TX and TX to RX (this is the usual pin labelling scheme with other converters).If you want automatic reset and upload - some precise soldering and trace-cutting is needed. Google it if interested.