So we put on this smart watch like a mitten necessarily left fist. So we remove the watch. Why not ... I have an iPhone 4, he came all battery in the case, so not bad. The worries 1: RunKeeper application I use does not work with the screen in landscape mode. So you have to be well reflect on the meaning of introduction of the iPhone in the case, either contort to see the screen. Not great. The screen is touch well, as with all such products. So good. The catch: I went jogging with and ... it takes super hot hand !!!!!!! I was eager to return to remove it! If you have headphones, you can safely call running, but without them, impossible to hear and to be heard at the same time unless you have a very flexible elbow! In short, I think this product is more practical for cycling or motorcycle for the race.