Large square reflective markers/ panels?

[ABN173]

Ok I can't remember where I read about these, but what were these for? I have seen them in Red/yellow/orange. (not having luck with the search feature)

Thanks,
Dale

 

[WillWagner]

Deliniation markers?
http://www.steelsoldiers.com/conversations/17358-delineation-plates.html

 

[Jones]

They're intended to make the rear of an MV a little more visible to any drivers following behind. The red reflective tailgate tape is being replaced by the yellow and red square panels. The solid yellow panels served the same purpose.