This is a 3-foot-long white audio cable that has been terminated with two TRRS connectors at each end. TRRS connectors are the 3.5mm audio-style connectors that you see on some phones, MP3 players and development boards. TRRS stands for “Tip, Ring, Ring, Sleeve,” which reflects the fact that, unlike a standard stereo connector, this actually has three conductors and a ground. Some devices use the extra conductor for a microphone (as in hands-free headsets) or to carry a video signal (as in some MP3/MP4 players). If you’re hacking on something that has a 4-conductor audio jack, being able to plug straight in will keep your build clean and simple.
We use and recommend this specific audio cable for our Spectacle product line.