Citizen Eco-Drive Power Reserve EM0187-57W Women’s Watch
It’s simple, yet technically more advanced than its competitors. Its power generating and storage system is built to last and work for many decades at a stretch; it’s the magic of the solar-conversion panel and the energy cell. It has no additional complex mechanism, so all you need to do is strap up and move-out in style.  Once fully charged, you can go for approx 8 months at a stretch.