How can a visual scan have good accuracy if they're measuring body fat? The band is only a microphone that analyzes your voice? A smart weight scale may not be

How can a visual scan have good accuracy if they're measuring body fat? The band is only a microphone that analyzes your voice? A smart weight scale may not be novel, but it works and works well. This product makes just as much sense as the Alexa glasses... which I don't understand either. Why have a microphone & speaker embedded in eye glasses where everyone can hear the response, when you can do the same thing for ear buds. The bigger surprise was that the glasses didn't show you anything visual. Amazon just needs to have another try at a smartphone again instead of strange experiments like this and the glasses.