The Image S4i employs a moving coil micro-speaker with controlled damping for smooth, full-bodied sound that's similar to a more expensive design. A dual neodymium magnet motor structure, in each of the 8.5 mm drivers, establishes the S4i's damping characteristics. The Image S4i works seamlessly with the iPhone 3GS, third generation iPod shuffle, second generation iPod touch, fourth generation iPod nano and the iPod classic 120GB. The headset features Apple's advanced three-button microphone and remote system that easily handles the voice and/or music control of Apple products. The Image S4i works with the iPod Classic, 4th-generation iPod nanos, 3rd-generation iPod shuffles, 2nd-generation iPod touch, and the iPhone 3Gs. Furthermore, the S4i remote is among the first to be fully compatible with the Apple VoiceOver feature on the third generation iPod shuffle, which allows you to hear the name of the playlist, song or artist with just the press of a button.