Snap is a wrist-worn MP3 player controlled by simple hand gestures and audio feedback. The consumer may control the device even in situations where conventional user interfaces would be difficult to operate. By examining the movement of tendons in the user's wrist, the device "reads" the hand gestures that control its playback, and reports status through wireless earbuds. The player and earbuds communicate using the user's skin as a transmission medium, with no wires required, and no radio interference. Songs are loaded and managed wirelessly with standard wi-fi. Although composed of high-technology parts, the complexity of Snap's brain is completely hidden.