4×12 aluminum sheet, was going to use this for the floor and firewall for a stoplight drag car, but sold the car. I'm not sure of the thickness I think it's .042 when I bought it I checked with a NHRA tech inspector to make sure it was thick enough to be used for a firewall. It could also be used for inner fender wells or door panels on a race car. CALLING WORKS BEST, NO PAYPAL CASH TALKS. 620-79three-097nine