The model 12 flame spreader is the same one used in the model-B burner found on most glass lamps.

 

There are two styles of model-12 fonts. The black one on the left is known as a "slant" side, and you can see how the sides of the font slant inward from top to bottom. The Nickel plated font on the right is a "straight" side font.

 

 

Model-12 fonts were sold in different finishes. The most common were brass, or nickel plated brass, but as you can see in the photo above they were not the only finishes available.