Blue3D(tm) Ft232rl Ftdi Usb to Ttl Serial Adapter Module for Arduino Pro Mini Port 3.3v 5.5v Support 3.3V, 5.5V with clone FT232RL chipset 500MA self-restoring fuse to protect the USB power from overcurrent Pin definition: DTR,RXD,TX,VCC,CTS,GND Tested by Blue3D(TM), the only authorized seller, before shipment and guaranteed not DOA. Can be used to program Arduinos. Quadcopters and more!