Its not new, its been around for awhile. Its pretty simple. call the local customs department at an airport. Schedule a time to take your weapon there. They will ask you to fill out a small form that asks for make, model, caliber, serial #, etc. then the custom agent will look at the form verifying that the info matches the weapon you've brought and stamp it. then you put that form in your wallet and when you are asked for it you've got it. Its basically proof that you owned the weapon when you left the states so that you don't have to pay taxes on it upon your return.