Yep, its a wheel on the end of a pole. They role it under points of the car that may be below 100mm.
e.g. Front, skirts, exhaust.
I tried to plead not guilty on one of my defect offences. But the defect notice is counted as one complete offence. So I was asked, were you driving an illegally modified vehicle. Answer was simple, yes.
$100, 1 point, - first ever law enforcement encounter and it was a major defect.
Good luck