I am now on my third Galaxy 42MM watch in less than two years. With any kind of active use - like walking or biking - the sensor on the back falls off and the watch is useless. I have received two replacement watches - the last one last November - and each time the same problem occurs. As soon as the weather got warm enough for me to sweat a little on my bike, the sensor fell off and the watch is dead. I tried to get a refund after the second watch, and of course was told that was not possible. Yesterday I went out and bought and Apple Watch and iPhone, and will never purchase another Samsung product. The watch cost $379 and the first one only worked a few months. The answer always is that there is water damage in a water resistant watch! I have seen many posts here from people with the same issue, but Samsung does nothing! I spent hours on the phone and did finally manage to get a free replacement watch each time, but I won't do that again. Sorry Samsung - you have lost a customer for life!