While I am sure that TSA will have no problem with the Mini Tritium Glowing Keychain, I don’t want to be the person who tests that statement. The mini-keychain uses the same radioactive material found in compasses, watches and other items that glow in the dark. You should never need to purchase batteries, since Tritium glows ‘naturally’ with our the need for a separate power source, even in complete darkness. The Mini Tritium Glowing Keychain will be able to go on glowing for approximately 10 years. It retails for $9.80 each and comes in a choice of a white or green glow.