1. This 7-speed rear derailleur (RD-TZ31-A) is suitable for 6/7-speed mountain bikes. It smooth gear shifting performance, allowing you to easily switch between different speeds while riding. 2. It features a direct mount/hanger mount design, providing flexibility in installation. Whether your bike has a direct mount or hanger mount configuration, this derailleur can be easily installed. 3. The black color gives it a sleek and stylish look, complementing the overall appearance of your mountain bike. It not only functions well but also adds an aesthetic touch. 4. Specifically designed for mountain bikes, it is built to handle the rigors of off-road riding. It can withstand rough terrains and vibrations, ensuring reliable performance during your adventures. 5. With the model number RD-TZ31A-Hanger, it comes with the necessary hanger for installation. This makes the installation process more convenient, saving you time and effort.