It's probably not fair to call this an Acu-Math; it's really a Sterling rule with the Acu-Math logo on one end. Presumably, Acu-Math was purchased by Sterling, either before or after Sterling became a unit of Borden. Still, even as cheapo plastic rules go, it's not a total loss. It's got engraved scales and a "Spring-Action Cursor"!
Never even removed from the package, like the other Sterlings I have.