Recently were announced about smart watches MATRIX POWERWATCH, that can be charged from your body heat, they are completely safe and waterproof, so if you are covered by rain or forget to take them off then nothing will happen to them. The biggest challenge of our time is not a big capacity battery, and usually manufacturers compromise, making gadgets more in size but they are more tenacious in terms of autonomy. In this model, all these amazing hours on another, you do not have contracts them every couple of days. They are very nice to look at your hand and come out for sale at a reasonable cost.