This product is like all products Runtastic I feel (Libra, etc ...): it works a few weeks / months, and then suddenly, poof, you start to know hell! The sensor has worked very well for 4 months, but in recent weeks he cut without reason in the middle of my races (or rather, he began to measure 30/40 beats per minute), which completely distorts the results. In recent days, he will not measure anything, even at rest: it is detected by my iPhone 5S but remains in "Waiting for data" indefinitely. The battery change and tightening of the belt are doing nothing. Wish me luck, I'm customer Gold (which I will not repeat), customer service Runtastic is one of the worst I've known.
