Deadening sheets (vibration damping material) 40 sheets Approximately 10cm x approximately 4.5cm, approximately 2.5mm thick Applying to the back of speakers, inside doors, and the trunk room can prevent surrounding rattling noises and road noise from outside the car. I personally recommend 32 sheets (8 sheets x 4 doors) for the inside of the doors. You can also create an environment where you can listen purely to the sound from the speakers. I actually use them in my own car as shown in the photos, and I feel a change in the weight of the doors, a sense of solidity, and an improvement in the sound. I'm waiting for any questions you may have.