Mi band 2 I purchased recently I couple of months ago because my tummy was coming out day by day and I used to go out for walk but how much calories was burn due to it, I was not aware of it and if you are not finding any effects on your body which will obviously come after some months, but if you get instant collection of how much calories are burn you get motivation to walk more.this is just what happened to me after buying mi band 2 , it shows you instantly how much calories are burn , before like I used to walk 20 minutes but now to make burn more calories I walk 45 minutes and it also show sleeping time, heartbeats.it also has led which has a very good feature.battery life is also good.it is most trusted brand for fitness so definately reliable and long lasting.