These were confiscated by TSA police from travelers.
You tried to bring WHAT on a plane?
A CS forum member said in Changi Airport they were strict and even checking his wallet contents.
This is why.
A person may carry a hidden credit card knife, to board a plane.
Metal detector may catch one with a metal blade. That is - until credit card knives with ceramic blades are made.
TSA Travel Tips - Credit Card Knives
image credit: www.spictech.com