This is a new old stock gas tank cap that is Balkamp (NAPA) brand and part number 4-1106.  This fits the following; Ford 1953-1963 full size cars (except Station Wagon); Lincoln 1954-1960; Mercury 1957-1958 and 1961-1963 (except Station Wagon and Meteor).  Part is new never used and in excellent condition and nice and clean.