Dont know what the gauge is, but it was meant to be a skid plate for my dad's porsche 924 Rally Car. Unfortunately, he died before we got the chance to build it.
Sorry for the crappy pics, I took it with my camera phone. I also couldnt find my tape measure, so for comparison, I put my 2 gal gas can in front of it.
http://img.photobucket.com/albums/v202/MegamanEXE/DSC00044.jpg
http://img.photobucket.com/albums/v202/MegamanEXE/DSC00043.jpg