THE  KEY IS FOR  VINTAGE WWII AIRPLANE COCKPIT CLOCK DIAL IT HAS  THE A M STAMP TO IT VERY NICE ITEM AND HAS THE  REF NUMBER  I DID THINK ITWAS FOR A CARRIAGE  CLOCK BUT TOO  SMALL , SIZE  IS 2" X 1 1/2" BRASS STAMPPED REF AM No6A /0606  ANY Q;S JUST ASK