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.