Microsoft has released a new update for the Microsoft Band app which is also accompanied by new Microsoft Band 2 firmware.
The Band app has been updated to version 2.3.21004 and brings:
Improvements for devices upgraded to Redstone 2.
The Band 2 firmware which comes along with the app update takes the Band to version 2.0.5301 of its firmware and delivers:
Track heart rate zones with your Band: improve your workout with notifications for heart rate zones.
When you are at 80% of your maximum heart rate, the color on the Band is orange, which changes to red when you hit 90%.
The firmware update should be offered after you install the app update.