Look, your child is destined for greatness. We won't dispute that. But, why wait until they can walk for them to rock their awesomeness? If they're crawling, they're ready to explore the world. Attach the Strider Rocking Base to a Strider 12 Bike and get them rocking. The rocking base doesn't just familiarize them with a bike, the rocking motion helps develop their balance, spatial awareness, and core strength. No batteries. No annoying sounds. Just pure, rocking fun. - Compatible with the Strider 12 Classic, Sport, and Pro Balance Bikes - When the Strider 12" Bike is attached this product is intended for ages 6 months - 5 years old for Strider Sport and Pro, and ages 6 months - 3 years for Strider Classic.