A. This flywheel cover is designed for mountain bikes and road bikes, featuring good adaptability and practicality. B. In terms of specifications, it has a 11T universal specification, which can meet the needs of most users. It is widely compatible with various mountain bikes and road bikes, bringing convenience to cycling enthusiasts. C. In terms of quality, it is manufactured using advanced technology, having good sturdiness and durability. The cassette flywheel cover adopts a cassette design, and the flywheel teeth can achieve a locking function. Paired with an XT lock ring, it can ensure a tight and stable connection. During cycling, it can effectively prevent loosening and displacement, providing reliable support for cycling. D. Its purpose is very clear: to provide protection and stable connection for the bike's flywheel. It can improve the overall performance and safety of the bike, making cycling smoother and more reassuring. Whether it's daily cycling or professional mountain or road cycling sports, this flywheel cover is a good choice. It is suitable for cycling enthusiasts in regions such as Europe, South America, Southeast Asia, North America, and Northeast Asia.