The listing, Nike + Ipod Sport Fitness System has ended.
This is a new but opened Nike + IPod Sport Kit. I purchased it from the Nike store a few years ago, but never used it. The white plug goes into any iPod nano and then syncs to the red and white sensor that goes into your shoe. Also works with iPhone 3s and later as well as the iPod touch, but you don't have to plug in the white plug. Just turn it on before you start your workout, and then go online afterwards to see your stats.