Environmental protection and health. Made of high-quality, high-strength PP plastic. UV resistant. High temperatures, ultraviolet light, and exposure can increase the activity of polymer molecules in plastics, raising the chance of oxidation. UV radiation carries high energy that can break chemical bonds in plastic, leading to degradation and fading. A special formula is used to slow down this chemical reaction and help prevent discoloration. Toughness and strength. The product is designed not only for firmness but also with flexibility in mind. Excessive rigidity may cause compound damage; therefore, both strength and flexibility are balanced to reduce the risk of breakage and injury. Specification: Diameter: 11 cm Material: Plastic & Steel Features: Stable metal supports, easy installation, individually adjustable Suitable for all bikes from 12 to 20 inches. Package Includes: One pair of bicycle stabilizers Note: Always ensure your child's safety when learning to ride.