It's ADHESIVE sheets of VINYL sound dampening material. I used it inside the door panels on the metal of my 2005 Mini Cooper S, it GREATLY reduced road noise. I replaced the speakers at the same I installed the sound dampening, so I cannot comment on whether it improved the sound of the speakers. I also trimmed sheets of adhesive felt and put pieces in the door to reduce rattle. I used about four or five sheets to cover both interior doors. It's been in the door for several months, adhesive is still going strong. I have no idea what the other reviewers were expecting, or perhaps the product has changed in the intervening years.
Rating: [5 of 5 Stars!]