i dont think they are illegal but there was an NFL player from my city who was busted with one.. i dont remember if it was at an airport or what, it might be a better idea just to ship it to your new address before you leave

im not sure about the BEST kind, but its probably safe to say that your local headshop, if they stock it, has a working mix that you could use. the stuff ive seen comes with rubber bands, a couple of handwarmers and the liquid in a plastic bottle with a temperature strip on the side to let you know when it is at a normal body temperature. ive seen powders also and have not had any experience with those, but i have used synthetic for pre-employment screens and passed 2/2 times. it is the BEST method to pass when you are positive no one is watching/searching you before/during the test. all you need to do is be CERTAIN its at body temp. i had a buddy once who forgot to warm it up and he submitted a 70 degree sample and me and him were chased off the labs property lolol