This is the piece in your iPhone 3G that pushes your sim card out when pushed with a paper clip or Sim Ejector Tool.

This will fix your iPhone 3G if you cannot eject the sim due to the mechanism being broken.

The installation is very simple and involves opening the iPhone, removing the old Sim Ejector Clip, Installing the New Sim Ejector Clip, and Closing the phone back up.

The process takes only 5 Minutes.