iPod Nike+ Shoe Sensor

Two pedometers do not increase accuracy. No need for the shoe one.

The 7G nano doesn't require the footpod, but it can utilize it. Here's why you might want to use it instead of the built-in pedometer.

Accuracy. The footpod is located on your shoe (or in it if you have the right Nike shoes). You're not going to get a more accurate placement than that. With the built-in pedometer, you really have to put it on your hip for best accuracy ... but then it's difficult to read while running. If you get an armband/wristband, then the accuracy may suffer due to your armswing.

To me, it's not contest. Get the footpod. It's only $20. A pouch goes for $5 on Amazon. It's worth it for the accuracy.

NOTE - Neither the footpod or the built-in pedometer will rival a GPS solution, but then again, GPS doesn't work on a treadmill or an indoor track.

NOTE 2 - there is more data collected when using the footpod. The footpod actually counts distance as well as pace. The built-in collects only pace, which the software will convert to distance ... at least that's how it worked on the 6G nano.

BTW, calories are calculated using a formula that takes into account your weight and distance traveled. Speed has very little to do with the calorie reported.