First, you need to buy a pair of NIKE+ running shoes, and then you have to have an IPOD NANO player to support 1 2 3 generations.
You have to buy 1 NIKE+IPOD, which is the receiver and sensor.
Place the sensor on the protruding part of the shoe and connect the receiver to the NANO player.
Then you can set a distance by yourself. How far can you set? 3 km, 1 km, 2 km can be set.
Then you start running, no matter how long or how far you run, the NANO player can tell you exactly, that is, send it to the earphone.