There is an old trope, “jack of all trades, master of none.” Polar may just have proven this untrue.
I purchased the M400 with few expectations. I have used Garmin watches for a while, and wanted to see what another manufacturer was doing with GPS watches. I was especially interested in Polar since they invented the first wireless heart rate monitor and I am a believer in heart rate training.
The M400 is Polar’s latest running watch that doubles as an activity and sleep tracker. And honestly, it does a good job with both. This is quite an acheivement for a device that costs less than $180 ($230 with a heart rate monitor).