In article .com,
says...

What are these fabulous 'microns' you speak of, and where may I obtain
them?

In case this was a genuine question, one micron = 1/25,400 inch.

In the case of vacuums, that's inches of mercury, just like in a
barometer.

--
is Joshua Putnam
http://www.phred.org/~josh/
Braze your own bicycle frames. See
http://www.phred.org/~josh/build/build.html