1. Its round shape and attractive design blend seamlessly, resembling a lollipop, adding vibrant joy to your child's childhood. (Note: Suitable for variablespeed bicycles) Reinforced wheels made of quality PU material We've long sought quiet and durable bicycle wheels, especially those offering shock absorption. 2. This quality PU jockey wheel is the solution. Additionally, the thickened 2.5 cm wheel (0.5 cm thicker than standard) minimizes bumps, ensuring effortless and comfortable rides. Double bearings and oversized washers Our training bike's double bearings have been optimized for smoothness and durability, extending wheel life. 3. Universal diameter and adjustable sizing: Our stabilizers feature a bracket with 5 adjustable holes, accommodating 12', 14', 16', 18', and 20' bicycles. 4. Plus, we've enlarged the washers to fully encase the bearings, eliminating worries about sudden bearing failure that could cause your child to fall. Safe and worry growth!