the Fitbit mobile app
app dedicated to breathe exercise "cardiac coherency"
will be translated in case of request.
step of 0.5s for inspiration and expiration time
indication of number of cycle per minutes and total number of cycles
vibration settings : none, light, strong
maximum time of exercise : 15 minutes
option for permanent screen or auto off
graphic indications for breath and time
vibrations at each change
permanent screen on and time leading for beginners.