Usb cover is what I know it as.
Dust and water resistance is it's only purpose and you can use it without it.
They go for about 6$ on eBay for a replacement
XDA Developers was founded by developers, for developers. It is now a valuable resource for people who want to make the most of their mobile devices, from customizing the look and feel to adding new functionality.
Are you a developer?
Copyright © xda-developers. Hosted by Leaseweb