Although it measures the body weight and perfectly correct, but the values for fat and muscle work is not measured but determined from tables or with linear approximation equations.
Example 1:
When two consecutive measures and in between a weight on the scale, so that you appear to be heavier in the second measurement, the fat and muscle percentage increases during the second measurement. If no weight is measured days later and this time is as difficult as in the second measurement with weight, you the same fat and muscle values obtained exactly as for the measurement of weight.
Example 2:
The same body weight will always result in the same fat and muscle proportions, no matter whether measured in dehydrated or neat water supply.
Example 3:
The correlation coefficients between weight and fat are in a series of measurements with 50 measurements and 0.9974 for weight and muscle percentage 0.9994. This is a perfect correlation, considering the measurement accuracy on the respective first decimal place. In other words: Here fat and muscle percentage are apparently not measured.
Conclusion: do not buy! I am not convinced that this scale measures the values given, I think she appreciates only.