TSA is an abbreviation for Transport Security Administration. It is a security agency, part of the US Department of Homeland Security, which was established after the 9/11 attacks. This body oversees the safety of travellers to and within the United States. When you fly to the U.S., your suitcase may be opened for the inspection by the TSA officers. And if they cannot get your suitcase open, they may force it open. So, to prevent finding your suitcase with a broken lock on the treadmill, we highly advise you to get a TSA lock.