Again, an area I was expecting to feel like a little more of a compromise does not in the slightest. Sooner or later there comes a time when the torch needs to be passed on. Rubber is no bueno. My son has run, jumped and played all summer long in these sandals. Im not sure if it’s thrown off by rapid fluctuations in my HR, moving around a bit on wrist during exercise, or what, but it often loses track of my HR, lags behind spikes and dips, and doesn’t seem to reach true peaks-For weight lifting, S health isn’t that useful; it can’t count reps on that many exercises and doesnt allow for custom workout design-I use an app (gymrun) that allows custom workout design; it doesn’t track HR or count reps, but you can manually enter reps and use S health (on ‘other Got this for my husband and now he wont turn it off No allergic reactions. The bad points:1 - You need the headset serial number to register for the 2 year warranty. Love these sandals they are sooo comfy and beautiful! I had needed a back up, back up.