A. This mountain bike spline bottom bracket screw is made of metal. It has good quality and high durability, which can meet various complex needs during cycling. B. Its specification is M15x12 spline, and each bag contains 2 pieces. This specification is compatible with many mountain bikes and can provide a precise and stable connection for your bike. It ensures that all parts of the bike fit tightly during cycling without loosening or shifting, making your ride safer and more reliable. C. Whether it's for daily urban cycling or exciting mountain off - road adventures, this bottom bracket screw plays an important role in enhancing the overall performance of the bike. It is suitable for various cycling scenarios and is a good choice to improve the quality of the bike and ensure a good cycling experience. D. This product is widely sold in regions such as Europe, South America, Southeast Asia, North America, and Northeast Asia, and is recognized and trusted by consumers.