The scanner did really funky things to all of my Acu-Maths, so they look a lot more stretched out than they should. Sorry.
Probably produced some time after the 511 (though i'm really only guessing on that), the 500 isn't nearly as nice a rule. As plastic rules go, it's ok (nice metal endpieces, and it's thicker than most) it doesn't feel as substantial as the 511, or other earlier Acu-Maths. It's got the cheap single-piece cursor, and even the cheat sheets on the back are less impressive.