a part sizing system in which the upper and lower tolerance limits are illuminated on the same bar graph display . electrical representations of the upper and lower tolerance limits are alternately coupled to the bar graph display so as to superimpose visual indications of both limits on one another , with each limit being distinguishable from each other by different light intensities . in one embodiment this bar graph display is disposed adjacent another bar graph display in the same housing . the other bar graph display is utilized to provide a visual indication of the output of at least one variable reluctance transducer which measures the size of the part under test . improved transducer excitation circuitry is also provided for insuring accurate measurements .