The backs of these cards were pieces of one of four different puzzles numbered 1 thru 4. Each card had one of two puzzle pieces, so 33 cards and 66 puzzle pieces total. Puzzle one consisted of 15 cards, Puzzle 2 had 18 cards, Puzzle 3 had 15 cards and Puzzle 4 had 18 cards. Backs can be found in either grey or white stock.