It is not only a watch.What's more,it is a uv indicator.The middle part will changes color when it meets the uv light or sunshine outside.There are 4 parts around the circle,which gradually grow darker.The darker the color,the stronger the sunshine.Each part indicate a different intensity degree of the sunshine.Compare the middle part color with the 4 parts,and find where is the sunshine .In this case,you can know what to do with the weather.