(forgive me if this is unnecessary review.  hazard of message board communication)<p>My understanding is that up until now they&#x27;ve been using a reference kilogram (Si sphere or, for the watt balance, a reference object) to measure Planck&#x27;s Constant.<p>Now that they are getting repeatable, converging results for Planck&#x27;s constant they can turn the process around; define Planck&#x27;s constant and then use the apparatus to generate a reference kilogram.<p>And so the beauty of it is that any sufficiently motivated team could assemble the equipment (either apparatus!) and manufacture a reference kilogram that would be just as good as anyone else&#x27;s.<p>Unlike the present state of affairs, where no matter how hard anyone wants to try, they simply can&#x27;t manufacture a reference kilogram better than the one in Paris.