I buy this fitness band almost 10 month later from mi.com from the recommendation of my friend.When I used this band I was totally shocked on using it because it was very small and accurate.Even the band tells me the time when was my sleep deep and when was my sleep light.The heart rate I measured from it was also very accurate.I also loved the display as it shows time as well as many other thing.It also reminds me when I worked too long to rest.I even bath by wearing it and nothing happend.So, it was a very good Fitness band.The battery life of band was also ver good at about 20-30 days I wear it without charging it.