What is a TSA lock, anyway?

A TSA lock is one to which only TSA officials have a key. You set the combination yourself and, if a TSA agent has to look inside your bag because they see something suspicious on the scanner, it can be easily opened with their master key. If you use a lock that’s not TSA-approved, the agent’s only way to get in is to cut the lock or the bag itself, possibly damaging it.

Many suitcases already come with built-in TSA locks but, if they don’t, you can buy one separately.