USB-TTL (serial RX/TX) adapter FT232RL with USB Mini-B connector (mini-USB).
The FT232RL is the standard USB to TTL brigde controller used by many Arduino boards. When ever you have a serial port with standard TTL logic level, you can use this little adapter to make it “USB compatible”.
For example, you can use it to program any Arduino board without USB connector by connecting the RX/TX pins of the USB-serial adapter with the TX/RX pins of the Arduino board (or directly to the Atmega pins).
Drivers for Windows, Mac OS and Linux are already integrated in the operating system.