Gum card manufacturers of the 1930s popularized the practice of producing "premiums " which were larger-format cards, redeemable with the exchange of a given number of baseball cards or wrappers at the point of sale. Carrying on this tradition in 1948-49 was the Leaf Gum Company of Chicago, which offered a larger-format pinup-sized premium to young chewers of their All-Star Baseball Gum in exchange for ten wrappers.

The known subjects currently counted at eight included some of the greats of the game's history, including Walter Johnson, Christy Mathewson, Ed Walsh, Grover Alexander, John McGraw, Lou Gehrig, Mickey Cochrane, and Babe Ruth.

The premiums themselves printed on lightweight paper were difficult to maintain in any reasonable condition and very few survived. Today, the premiums are very, very scarce. Due to the relative recency of large-format grading company holders, population reports may not be the best gauge for scarcity, but there is no question that these premiums are very difficult to obtain.

These particular examples of Hall of Fame pitchers Walter Johnson and Christy Mathewson refer to them as "baseball's immortals," a statement that holds true even today. The grade on Johnson's can primarily be explained by the piece having been folder, once in half vertically, and then in half horizontally. The MK qualifier on Mathewson's refers to a pencil marking on the blank back, something not affecting the front image.

Despite the low technical grades on each, these are very scarce and unusual premiums from a very difficult-to-find issue.