This is the best! Especially for grandchildren! Now they may not use it for very long, but several times a day. If they get angry, I would say it's not so safe. However, everyone enjoys watching them and teaching them their gentle play. It's easy to connect, turn on the button, be alert and it's an instant lock. I would say 18 months to 8 years if you play well. I wouldn't put more than 4 kids in at the same time because they're bumping into each other. Have fun!π