We have 2 Brown Porcelain Door Knobs Vintage items.  The center bar is not with this set it is just the knobs and metal backs.  They measure about  2 1/2" across the top front of the knob x about 2 1/4" in D.  The metal building up to the porcelain on the knobs is metal and fairly well rusted.   They have a marble like design in browns/blacks on the porcelain.  1 has ?black paint splatter on the side to back in one area.  I would say they are in fair condition. 

2 Door Knobs Brown Porcelain Vintage