These body composition analyzers adopt a tetrapolar, eight-point tactile electrode system that separately measures impedance of the arms, trunk, and legs at six different frequencies (1, 5, 50, 250, 500, and 1000 kHz) in the InBody 720 or three different frequencies (5, 50, and 250 kHz) in the InBody 430, for each segment.
Source: wiktionary