What’s the role of magnetic ring?

When choosing UOTEK USB cables, some customers are curious about a cylindrical thing near the USB port. But what’s its effect? Simply said it is the circular, anti-interference magnetic ring; or absorption magnetic ring and ferrite beads have filtering effect, filtering the high frequency noise. 

Why use anti-interference circular design? Computer case, for example, its motherboard, CPU, power supply, and the IDE cables are working in high frequency condition, thus lead to lots of space stray electromagnetic interference signals. And the signal intensity is several times to dozens times if compare with outside case. For USB serial ports without circular, there is no shielding measures in this space. Thus these USB cables become a good antenna to receive all kinds of messy high frequency signals in the surrounding environment. And these signals superimpose on the original transmission signal, even change the useful signal on the original transmission. It's easy to get problems.