A. These are a set of disc brake caliper screws for mountain bikes, designed for the braking system of mountain bikes. B. In terms of specifications, there are two different sizes of screws available: M6x18 and M6x20. These options can meet the diverse needs of different users, allowing you to make a flexible choice according to the actual usage scenario and bike configuration. C. These screws have good compatibility and can fit well with the calipers of mountain bike disc brakes (commonly referred to as "caliper housings"). During the installation process, they can be perfectly integrated with the braking system to ensure stable operation of the brakes, providing a reliable safety guarantee for your ride. D. The screws are made of metal and have a decent quality. The metal material gives the screws good strength and durability, enabling them to withstand the large pressure and friction generated during the braking process of mountain biking. They are not easily damaged or deformed and can maintain stable performance even under long - term and high - intensity use. E. Functionally, they are important components in the mountain bike braking system. Through precise installation and proper use, they can effectively improve the sensitivity and reliability of the brakes, allowing you to control the speed of the bike more safely and smoothly. Whether you are riding on rough mountain trails or flat roads, these screws can provide a good braking experience.