ACC carpet underlay sound dedener for A,B&E $40

Similar- but mass backing is physically attached to the entire carpet (see pic).

I had mass backing on my carpet but I put this same Sound Deadener in my 69 Dart first. Awesome stuff- lay it in the sun for abit and it lays in the car real nice. I think it was 4pcs total? This stuff makes a BIG difference in my opinion!