These foam puzzles have magnetic backing so pieces will stick to most metal surfaces. Pieces fit snuggly and are still easy to remove. Durable foam is easy to clean. A terrific set that includes one each of our Upper Case Letters Magnetic Puzzle, Lower Case Letters Magnetic Puzzle, and Numbers Magnetic Puzzle. Each individual set contains 3 puzzles. Sold as 2 sets for a total of 6 puzzles.