FTDI FT232RL USB to TTL serial adapter (3.3V or 5V selectable)
This USB to FTDI serial adapter has a switch to select the data pin voltage - 3.3V or 5V. This makes it compatible with our full range of Arduino-compatible boards as well as the ESP8266 wireless boards and others.
Please note that the pin labelled 5V is always at 5V, regardless of the 3.3V/5V switch position. Only the RX/TX levels are affected by the switch.
You'll need a mini-USB cable to connect this to your computer.