The Nike+iPod Sport Kit was announced on May 23, 2006. A press released stated, “Nike and Apple today announced a partnership bringing the worlds of sports and music together like never before with the launch of innovative Nike+iPod products.” The two-piece wireless system included an oval sensor that was placed inside a Nike+ shoe and a 30-pin plug for the iPod nano.
Software on the iPod nano would connect to custom Nike+ footwear or any shoe with the Nike+iPod sensor attached and provided information on time, distance, calories burned, and pace on the iPod screen. In addition, “A new Nike Sport Music section on the iTunes Music Store and a new nikeplus.com personal service site help maximize the Nike+iPod experience.”
This kit was sold for $29 and included an in-shoe sensor and a receiver that attached to iPod. I used this device with both an iPod nano and with the first two iPhone models both on a treadmill and during my walks and run/walks. I attached the device to my running shoe laces with a purpose-built case that held the oval sensor. A later pair of shoes had a built-in slot in the arch of the sole that held the sensor.
Source: Apple.com