The thing I love most about the Mi Band 4 can be shown in the picutre on this page.

It's the battery life. 

I was meditating and I received an alert on the band that it needed charging. I should have charged it first or put it on silent mode before meditating.

But the amazing thing about this fitness tracker is that it rarely needs charging.

In the picture you can see that my Mi Band 4 lasted 25 days on a single charge. And there's still 4% battery remaining. 

My old FitBit would need charged every week. That was a nice device, but I like how I can get three times the usage between charges with my Mi Band 4.