68 F/B rear seat carpet underlay ???

Thanks Tom, I took these seats apart about 2 years ago and put new seat covers on. The original paper board and carpet were in such bad shape that it was hard to tell what it looked like. I assumed it was some rigid type of thin fiberboard and that it's purpose was to provide a firm flat surface for the carpet to bond to .

Can you feel the grooves in the metal below the carpet on yours ?