This is a bottom bracket fixing screw suitable for mountain bikes and 412 folding bikes. The screw is made of metal, specifically titanium alloy. This material ensures that the screw has excellent quality and durability, can withstand significant pressure and friction, and is not easily damaged even after long - term use. Its specification is a square hole M8x15mm. The precise size design allows it to perfectly fit the corresponding bike models, and the installation process is easy and convenient. Moreover, this screw has a waterproof function, which can effectively prevent moisture from invading, avoiding performance degradation and shortened service life due to rust and corrosion, and ensuring the stable operation of the bike's bottom bracket. Whether you are facing complex and changeable road conditions during mountain biking or performing frequent folding operations in the daily use of a folding bike, this screw can play an important role, providing reliable support for your ride and allowing you to ride with more peace of mind. It is suitable for multiple sales regions, such as Africa, Europe, South America, Southeast Asia, North America, Northeast Asia, and the Middle East, and can demonstrate excellent performance in different environments. In addition, it has an authorized own - brand, and its quality is trustworthy.