Nike+ Standalone Sensor
The Nike+ Sensor: Run tracking made easy The Nike+ Sensor makes it easy to track your time, distance, pace and more while you run. When your training is finish, upload your run data to Nikeplus.com, world's largest running club, where you can monitor your progress, join challenges, map your runs and connect with friends. The sensor is sold individually, so it's ideal if you're due for a replacement, want another one for a second pair of Nike+ ready shoes or need one to hook up to your Apple device. How it Works Simply place the Nike+ Sensor under the sockliner of your left Nike+ ready shoe and start running to sync it with your Nike+ SportWatch GPS, iPhone 3GS  or other Nike+ tracking device. The sensor measures your pace, distance, time elapsed and calories burned. This information is transmitted wirelessly to your Nike+ tracking device for real-time feedback while you train.