Sturdy Material Made from aluminum alloy for wear resistance and lasting durability. Provides a sturdy, reliable mounting point for long term use. Practical Function Tail hook extender eases the tension of the spring after pulling, reducing concerns during operation and helping maintain smooth performance. Easy to Use Simple installation: fix the tail hook extender to the existing frame tail hook with screws, then install the rear derailleur to the tail hook extender. This straightforward setup supports quick upgrades or maintenance. Exquisite Design Hollow, lightweight construction combines a refined appearance with strength, helping keep overall weight down without sacrificing rigidity. 23 Use Scenarios Scenario 1: Bicycle upgrade or where the tail hook mounting is used to attach a rear derailleur. The extender provides a secure, stable mounting point during installation. Scenario 2: In or roadside maintenance where relieving spring tension is needed to simplify derailleur removal, adjustment, or reassembly. Scenario 3: On lightweight or spaceconstrained frames where the hollow design minimizes added weight while maintaining strength for dependable derailleur mounting during rides or field repairs.