The real flagship DMM from HP is still the 3458A, it remains the favorite of most high end cal shops and is used by many as their primary shop standard.? capable of accuracy to a few ppm in some modes, it is really a marvel of engineering a every level.
oddly, it is the fluke 8506A that was the preferred standard for true RMS AC measurements.
other very high end units include Datron and Schlumberger models.
all the best,
walter (walter2 -at- sphere.bc.ca)
sphere research corp.
