'The' Mi Band from Xiaomi, personally I didn't like this band 'at all'. I've used other fitness bands and I thought that I should give a try on Xiaomi's first attempt on this field. But they have made a perfect dissapointmet. Well all the other bands which are ruling the market basically works on the same principle. You have to wear it at the time of working out or you can have it all the day long to track upon your calories. Simply they have an accelerometer integrated and through the arm stroke movements they can trace your footsteps and counts them. But you have to have a smartphone to pair it over bluetooth to keep the records with you, otherwise you'll end up wasting all your bucks. It doesn't have a LCD which is a big-big pain, believe me. The band isn't that good in looks too. Overall you're not getting anything good with this band, go for another one.