MATERIAL: set uses high quality, safe and non-toxic plastic. Plastic edges are rounded and smooth with no edges or corners, improving safety and stability. It makes parents safe and makes their kids happier.^ EASY INSTALLATION: After inserting two AA batteries into the train toy, you can turn on the switch to play (you need to prepare the batteries by yourself). Domino Placement - Insert the domino slot into each end of the slot.^ CHILD SAFETY: These plastic domino products are made of non-toxic plastic that is safe and will not fade. The edges are smooth to ensure children's safety when playing. We do not recommend it for children under 3 years old.^ CULTIVATE CHILDREN'S MULTIPLE SKILLS: Dominoes are a pastime activity that encourages creativity and builds confidence. It is good to develop the intelligence and creativity of the participants. More importantly, you can encourage participants' will and teamwork.^ HOLIDAY GIFT: This is the perfect gift to stimulate children's thinking. Children can play together at the party and have many happy moments. Parents can also interact with their children. Suitable for children over 3 years old. Please ignore the 6 years and older stated on the product. Thanks for your support.^