Originally Posted by Bart

I think there's a misconception about the purpose of secondary screening. We are not concerned that your blue jeans have rivets. Nor are we concerned that bras have underwires, belts have buckles, etc.

After asking you, the passenger, to remove all metal objects from your pockets or your person, we are giving you the first opportunity to avoid secondary screening with the hand wand. If you alarm the WTMD, we give you a second opportunity to remove anything else you may have forgotten. If you then alarm the WTMD, we have to conduct a more intense inspection with the hand wand. Before being inspected with the hand wand, you are asked, for the third time, to remove anything else that is made of metal. You are also asked if you have any sort of medical implants or other devices that could explain why you alarmed the WTMD. Then the hand wand inspection begins. The hand wand is designed to detect smaller metallic objects than would be detected by the WTMD and is held in much closer proximity to your body than is the WTMD.