An official website of the United States government
Here’s how you know
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
Secure .gov websites use HTTPS
A lock (
A locked padlock
) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.
as adopted by the 104th National Conference on Weights and Measures 2019
Notice regarding the latest version of NIST Handbook 133 | PDF