Xaiomi is famious for their innovative products and they did this again by thier mi band 1s the band hai militry grade sensor and the most importantly the heart sensor this time the heart rate sensor is presize and does the perfect job the band is light in weight Nd is easy to carry one dont feel it in hands it moniters the diffrent phases of sleep very accurately thought it not very accurate but is very fit for enrty level fitness trackers I think one should defenatly buy it and try it go for it wont dissappoint you