The Polar S625X is like having a performance lab with you on every workout. All the heart rate, running and cycling data you will ever need is available right on your wrist. The S625X delivers continuous running speed without relying on where satellites are positioned. With the optional cycling and power sensors and enhanced training tools like the Polar OwnOptimizer™ recovery test, plus altitude and ascent for route profile, the S625X lets you cross train and put the power of information to work for you.