them (which would remain exclusive to the iPod Shuffle series until iTunes 9.1). Furthermore, older versions of iTunes allowed an iPod Shuffle playlist to be viewed and changed while the unit is not connected; changes would be synchronized the next time the unit is connected. However, this functionality was removed in iTunes 7. Due to superior audio technology in the SigmaTel STMP35xx SOC and SDK, the first generation had a better bass response than a fourth-generation iPod, according to a review published days after its release. The front of the iPod Shuffle has buttons for Play/Pause, Next Song/Fast Forward, Previous Song/Fast Reverse, and up and down volume adjustment. On the reverse, it features a battery level indicator light (activated by a button) and a three-position switch to turn the unit off or set it to play music in order or shuffled. It plugs directly into a computer's USB port (either 1.1 or 2.0), through which it also recharged its battery, which has an expected life of around 12 hours. The USB plug has additional pins for proprietary accessories and, when not in use, can be hidden beneath a cap. A second cap, included with the unit, has a lanyard attached which allows the iPod Shuffle to hang around the user's neck. As both already supported by its larger relatives and suggested by its design, the Shuffle can also be used as a USB flash drive - a feature further facilitated by the dropping of "Macintosh" (HFS Plus) format: all Shuffles are formatted to FAT32 regardless of the operating system used for restoring them. iTunes also allowed users to reserve part of the capacity for storing files, by limiting the space that would be used for storing music. 2nd generation On September 12, 2006, Apple announced the release of the second-generation iPod Shuffle, calling it "the most wearable iPod ever". First shipments of the unit were slated for an October 2006 arrival, but actually started shipping on Friday, November 3, 2006. The second generation initially featured a lone 1 GB model in a silver brushed aluminum case, similar to the second-generation iPod Nano and the older iPod Mini. The new model was less than half the size of the first-generation model at 41.2 x 27.3 x 10.5 mm (1.62 x 1.07 x 0.41 in), and was the size of the iPod Radio Remote. Apple claimed it was the "world's smallest MP3