Fitbit Ionic
29.23 mm, Aluminium
Fitbit Ionic
29.23 mm, Aluminium
According to tests, Polar belts should be compatible:
www.digitec.ch/de/Comparison/6191015-6191018
But apparently the values of the watch are already quite good and almost exactly the same of the strap.
fitnessmodern.de/fitbit-ionic-test/