This is a replacement lid for a vintage Revere Ware 12 inch skillet frying pan. It's the largest and most difficult to find size in the Revere copper bottom stainless cookware line. The exact measurement of the inner rim is 11-3/4 inches diameter - there is a slight overhang above the inner rim of course. The lid is clean and shiny but does have two dings or dents on the outside edge. They don't affect the seal or cooking performance whatsoever as they don't extend into the inner lip.