Brass is often used in manufacturing due to its corrosion resistance and durability. It's a common choice for components that come into contact with air or water, such as air pumps.

The 8mm measurement you mentioned likely refers to the thread size. Thread size is important because it determines compatibility with other parts or devices. In this case, a 8mm thread size would indicate the diameter of the threaded portion of the nozzle adapter.

It's important to ensure that the nozzle adapter's thread size matches the valve or nozzle of the item you're trying to inflate. There are different types of valve systems, such as Presta, Schrader, and Dunlop valves for bicycle tires, each with their own specifications.