These dozen eggs come already stuffed with small pull back animals that run when you let them go. They are adorable looking and cute. These are suitable for children 3 years and up. No batteries are needed to play with these. They are perfect for putting in Easter baskets or hiding for egg hunts. They eggs are durable and could be reused next year! I love the cute little animal designs, and they are really easy to use. My grandkids will enjoy these almost as much as me!