Prema is a German company that is making precision measurement stuff. Today they do not make multimeter anymore but they make uber-calibrators: Josephson junction arrays.
This 7.5 digit meter was inclusive calibration report and calibration. It was calibrated september 2010. Regarding DC stability only a Transmile and Datron 7,5 digit meter are more stable (and a dozen of 8.5 digit meters) . This is 20 ppm/year at 3 VDC.
Very funny is the fact that it has a beep function for continuity. This is not the meter you use for repairs. But the nice thing is that it is well suited for this. Its reference is always standby so no warming up. It is very good protected and shielded and it is true RMS, AC+DC and up to a bizar 1MHz (crestfactor 7)