Siless 50 mil (1.3mm) 26 sqft Car Sound Deadening mat - Butyl Automotive Sound Deadener - Noise Insulation and Vibration Dampening Material ( 26 sqft)

Good price, quality.

I used this to insulate the firewall of my 74 Charger while I had the heater box out as the factory insulation turned to dust. It stuck great and was easy to cut and install. I'll also use it on the floors to reduce noise and heat.

I used this for my car doors during speaker upgrade. Audio sounds better and road noise significantly less. Highly recommended.

Easy to apply, helped lower the noise in my car.

When I finish the project I will know if it is a good sound barrier other than that it’s great