Do NOT use external locks such as padlocks because they increase the risk of damage to your case during transit. You may use integrated locks that are internal to your case and essential in helping it remain closed, but please be aware that carriers do not have TSA keys or the ability to open such locks in the event that your label comes off and they need to open your case during a package trace. Locks will also be a problem in the event that Customs needs to open your case during an international shipment.