This is a brand new c110 annealed soft copper sheet.
It is commonly used for roof flashing as well as crafts, art projects, and hobbies because of its workability and formability. It is also a perfect choice for electrical experiments and projects because of its excellent thermal conductivity and electrical conductivity making it a low resistance path to carry current.
It is 16-oz copper (22 Mil) that is 12" wide by 8' long. 16-oz copper is 0.0216" thick.
(ato95)