You can now lock your bags again, and know whether they have been searched by a TSA agent, or violated by an unknown person. If you don't use TSA approved locks you must leave your checked luggage unlocked so the TSA can open it for inspection. Only this TSA approved lock lets you know if your bag has been opened, with its unique green light/red light security window. If the window shows green, your bag has not been opened; red it has been opened. Black, Red, or Yellow.