The NIST-4 Kibble balance was used to measure Planck's constant to within 13 parts per billion to help redefine the kilogram.
https://s3-us-west-1.amazonaws.com/h...al_balance.jpg
More:
[url]https://en.wikipedia.org/wiki/2019_redefinition_of_the_SI_base_units#Kilogram[url]
Previously:
https://www.homemadetools.net/forum/...962#post133830