The Wahoo Blue SC is the worlds first Bluetooth Smart (4.0) cycling speed/cadence sensor made for the iPhone 5 4S, iPod Touch (5th generation), iPad (3rd & 4th generations) & iPad Mini. This sensor &. App combination transform your iPhone into a powerful cycling computer. The Wahoo Blue SC connects wirelessly to the iPhone 4S or iPhone 5 (no Wahoo Key or Bike Case required) & tracks your cycling speed, peddling cadence & distance through the free Wahoo Fitness App. The Wahoo Blue SCs exciting new odometer functionality tracks the lifetime distance of your bicycle & stores the data in memory. Whether you ride with or without your iPhone, as long as you have your Blue SC you will always know the total mileage of your bike. Using the free Wahoo Fitness Odometer App, you can sync all your data once in range of your iPhone 4S, iPhone 5 or new iPod Touch or iPad & see the lifetime mileage of your bike by week, month & year. in addition, the Blue SC works directly with other popular cycling Apps, such as Cyclemeter, Strava Cycling, Map My Ride & Runtastic Road Bike.