Topps' first full venture into the baseball card market was the 1951 Red Back and Blue Back card sets, which featured 52 cards in each set, with each card part of a flipping game kids could play. Inside these eight tightly sealed packs could be pristine cards of Hall of Famers Yogi Berra, Duke Snider, Phil Rizzuto, Bob Feller and Warren Spahn. Hobby fresh packs present in a strong EX-MT/NM condition.