Cheap American imports…

Empire steel framing (not) square. Copyright © 2018 Wayne and Elizabeth Saewyc

You get what you pay for. I was mildly surprised to find a US-made square at the local lumber/bigbox store, and it was cheap, and I needed one.

It is 1/8″ out in 24″.

And how do I know this? because I have four parallelogram blanks in my shop. And an oddly shaped straightedge because it is useless as a “square”.