Vintage Maple Leaf Brand Frankforts Tin Over Cardboard Rare Boston Advertising Sign. Available here is an excellent piece of 1930s-1940s American advertising. This tin over cardboard (TOC) sign advertises the Maple Leaf Brand Frankforts produced in Boston, MA by P. These were a popular food item for many years. The sign is in excellent original and unadulterated condition. Please excuse the glare in the photographs. The original hanging chain is present. There is a maker’s mark on the reverse side bottom border. Keene Ad Services, 38 Church St. There are some signs of age and use including but not limited to: scratching, discoloration, paint loss, chips, and dust. Please view all photos and contact me with any questions that you may have. Measurements: 11″x 7.5″ approximately.