This set is one of those rare issues that can pose a serious challenge to those who seek rarity. The 1968 Topps 3-D cards were a test issue that entered the scene with a new look that was unlike anything ever seen before. A couple of years later, Kellogg's would create a card loosely based on this Topps creation, but they weren't quite the same in terms of quality or scarcity. The Roberto Clemente card dominates the set as the only major superstar. Other nice additions include Tony Perez (a Hall of Famer), Boog Powell, and Rusty Staub (both fan favorites) to name a few. Today, due to very limited production, the cards are very hard to locate in any grade making this the set a tremendous challenge. To read an in-depth article, click here.