Children will discover through trial and error how to stack the wooden disks on the tower and develop logic building skills. Each disc has a certain number of color-coded holes that fit against the colored pegs attached to the tower. Wooden Stackable Puzzle is recommended for children 3 years. The Wooden Stackable Puzzle is perfect for classroom or playroom activities. Diameter of each of the 9 pieces: 3.95". Constructive Playthings is committed to providing safe, compliant products and a healthy, safe working environment worldwide. We require that all products meet all applicable federal regulations, which we review on a continuous basis.