Oh, wow, this is so bad. m usually means "milli" not "micro". At least they could have used u instead of µ, which is a more common replacement when you don't have the keyboard character available.

Just wait until you see the actual dimensions of a 2x4!

I owned a house once that was balloon framed, with 2"x4" black walnut studs in the walls.

They just don't make things like they used to. :)