These converters can be used to (safely) connect the serial port on a Robo Rio to a serial line on an Arduino (e.g., to allow the Rio to send commands for lighting control to an Arduino, or to ask it for information being obtained from a Pixy camera or sensors that are wired to the Arduino). They allow signals (such as serial port data) that may be running at different voltages between the two devices to be translated cleanly (e.g., between the 5V used by an Arudino, and the 3.3V used by a device such as a RoboRio).