Intended for use in custom Nike sneakers. *BUT* If you don't have that particular series of shoe, the sensor will work in any footwear (e.g., lace the sensor button into tongue), or even anywhere on body. With free iPod/iPhone app, monitor all activity, maintain charts and goals, develop custom workouts, etc (similar to a fitbit, etc.). If you have an iPhone, you don't need the included receiver, just the transmitter (i.e., body-side disk).
Unit in good condition. Included in sale is a new battery. As soon as battery is inserted, device become pairable with your smart device.
Fast shipping, no hassles. Check my feedback.