Produced by the Philadelphia Gum Company (the same company that produced the Philadelphia football card sets of the 1960s), the Swell Bubble Gum "Sport Thrills" series was a 20-card set that featured a black-and-white photograph depicting a great moment in baseball history, with the story of the event explained on the back.  Featuring memorable events throughout baseball history up until the immediate postwar era, few "sport thrills" are more important than the debut of Jackie Robinson, depicted here just one year after its occurrence.  Graded VG-EX 4 by PSA, the card is exceptionally sharp for the grade, and even well-centered for the issue (the set is absolutely plagued with centering problems to the point of miscuts).  With eye appeal befitting an EX-MT card (or, in a different time, perhaps better), the fatal flaw is a very light surface wrinkle near the top edge in the center, likely a flaw in the paper rather than a wrinkle that occurred due to wear.  A tremendous card, which has rapidly escalated in value as Robinson has become more important in the hobby.