They're simply internal cables, such as IDE (hard drive) or floppy cables, that have been rolled up so that they are more compact and take up less space. Obviously, the ends where the connectors are aren't rolled up, but the length of the cable is. The point of this is to have a cleaner, more organized case interior, as well as to help with air flow circulation and cooling. I just ordered some from ucdweb.com - you can find pictures there. 🙂