Source: http://www.engadget.com/2013/02/12/armour39-hands-on/
Under Armour has always touted the scientific underpinnings of its sports apparel. From moisture wicking to heat trapping and everything in between, the company is quick to assert that it isn't just another athletic clothing company. But, performance enhancing shirts and pants have their limitations and, arguably, performance monitoring is a far more interesting and burgeoning field. In 2011 it dabbled with E39, a compression shirt with a space to insert a "bug" that included and accelerometer and heart rate monitor. Today, at an event in beautiful, chilly New York City, it officially unveiled the next evolution of that toe-dipping, Armour39. While there may be a shirt in the future, for now the system consists of a traditional chest strap, an iPhone app and an optional watch for those that don't like to carry their expensive smartphone with them on runs.