The Wahoo Fitness Fisica Sensor Key for iPhone is a simple solution to connect your iPhone to all of your ANT exercise sensors and ANT GPS devices. It wirelessly pulls data from ANT heart rate monitors, cadence sensors, and GPS devices, integrating exercise savvy metrics into powerful iPhone applications for real time analysis. It's compatible with a wide variety of iPhone applications, such as Wahoo Fitness, Runmeter GPS Pedometer, Cyclemeter GPS, and Map My Fitness. It doesn't run on a battery, so you won't need to worry about charging it up before working out. Additionally, it transmits a signal up to 10 feet, allowing you to stash it in a pack, wear it on an armband, or stick it in your pocket.