The 1951 Topps set is the cornerstone of the modern baseball card industry although less popular than the company's 2nd set release. Topps' first set consists of 104 base cards with 2 traded/update cards for a total of 106 cards in the collection. The A-series cards are commonly referred to as Red Backs, while the B-series cards are commonly referred to as Blue Backs, but they are should be considered as two different series withing the same set: #A1-A52 and #B1-B52. It is loaded with some of the top stars from the day.