Coming through ATL checkpoint with a duffel bag carry-on that has a separate end pocket. I was connecting from international to domestic. X-ray searcher called for a bag check. After checking the entire main compartment, the TSO found a TSA-approved lock in the end compartment (the kind with a 3-inch cable). Nothing else was in the compartment. I try to always have a spare, just in case I end up unexpectedly checking a bag on the return trip.

The bag checker conferred with the x-ray searcher and said she'd never seen one before (?). He also told me that TSA-approved locks are for checked baggage.

I count myself lucky it didn't get confiscated.

I have also 'surrendered':

-a length of surgical tubing I was using to rehab a shoulder injury. It could
be used to throttle someone.

-zip ties (about 6 inches long) because they could be used to handcuff
someone.

-a 7-inch crescent wrench I used for bike repairs. It opens to 3/4". Forgot
it was in my carry-on. Tools are not allowed.

- a quarter-sized disk with four 1/8" screwdriver 'blades' on my keychain.
A gift from my father many years ago. Used occasionally for emergency
repairs. Also a dangerous tool.