This car audio converter plays audio from Aux or USB inputs through the radio by channeling the audio through an unused radio frequency. The Aux/USB inputs as well as the display, which displays the radio frequency used, are resonably intuitive. The ports themselves act as effective signifiers for their respective affordances. The display clearly displays the selected frequency.
The poor design of the converter is apparent in the controls on its sides. These controls allow the user to change the selected radio frequency to match the frequency selected by the car’s radio. A user will often need to use these controls while driving if a selected frequency has interference. To change the selected frequency, the user first has to press the “CH” button then use the arrow buttons on the opposite side of the converter to adjust the frequency. This process is not obvious from the labels on the buttons and is difficult to figure out, especially while driving. Additionally, these buttons are difficult to see when the converter is plugged into the car. Because of this poor design, performing the basic tasks necessary to operate the converter are difficult and confusing. Doing this while driving is dangerous and difficult, and has nearly caused me to get into several accidents.
Finally, the labels on several of the buttons seem to imply that the converter will allow the user to control the audio from the device (using the play/pause and fastforward/reqind buttons), but this does not seem to be an affordance of the product.