While I haven't used 'em yet, friends put 2 laminated name/address/contact info tags on their cases/baggage and wedged the gps tags between the laminated cards (as a sort of external gps tag envelope), hung at the very same spot as the cards and sealed shut via cable ties. It cannot be seen, and it's outside the (aluminum) case. Also fairly difficult to remove! Inside a plastic case is prob even better; just have to test 'em in your particular setup! I believe they work in the SKB cases as they are aluminum frame w/ double hard plastic shell. How I wish they existed for bicycles as a kid and motorcycles as an adult!!! lol now