1DURABLE MATERIAL - High quality metal and rubber. These heavy duty rear wheel are very sturdy and durable. 2EASY TO INSTALL - Comes with fittings, all mounting hardware and installation instructions is included.The support brackets are individually adjustable. 3ADJUSTABLE - These training wheels are suitable for 16 to 24 inches children bicycles and you can adjust it fit bike of your kids. 4KEEP SAFETY - This set of heavy duty rear wheel stabilizers assists young learners to ride bicycle until they find a sense of balance on the bike. 5WARM TIPS - Some bikes like those one-armed-frame bikes and bikes that rear frame tail hook angle are particularly large are not suitable for this training wheels.