I heard a lot of positive comments about this product so bought one to try it myself. Turns ojt to be a great product.
The 899 band by MI says to have battery life of 30days. Sound silly as at this market products at most ha e 7days battery backup but as said jt astonished me by running 42days in the first charge only. With highly accurate pedometer and sleep tracker its definitely a product you should buy without hesitation.
But some things I found which could be improved was feature. Better app support and a sleep tracker not only for night but whenever you sleep.