Metal Detectors at the Post Office

[Fishersjohn48]

What do the metal detectors at the post office detect? I recently mailed a box of various knives, some of them large butcher knives to Tyler for some much needed re sharpening. Walked through the door with the metal detectors on both sides and nothing happened. The mass of steel was much larger than any gun I might have been carrying. Are they just for looks or are they set to only pick up steel with polymer(plastic) around them?

 

[Kitty]

I always thought they were for decoration. I've shipped several types of car parts without a beep.

 

[eldirector]

They aren't metal detectors. They are RFID readers. Same as any convenience store. I assume a lot of the USPS property has security tags, and these scanners would read them as you pass through.

For the tin-foil crowd, they might also be able to read any unsecured RFID chip, like in clothing, gift cards, etc....