It's a vintage original airbrush on acetate, with the base painting being on illustration board. 

It was used for BOTH the San Francisco 49ers AND New York Giants ... along with the fighting Irish. 

On top of the base piece... which is black and white airbrush, there is a sheet of acetate with the IRISH logo on the helmet.

Then there is another sheet of acetate airbrushed in the New York Giants colors. 

Yet another sheet of acetate on top of that with the 49ers colors. 

I am guessing mid to late 80's for this piece, with the heavy use of airbrush. Possibly for playoffs or something?

I do NOT see a signature.

I bought a rather LARGE collection of original advertising art, and this was in the mix. The vast majority was work by

Joe Spencer.