Bad move (Score 2, Informative)

I use to sell RFID. The implantable IDs have a tendencey to migrate. You cannot control where they go and could end up in your heart. If you are truly concerned with universal access I would suggest looking at a Bluetooth Headset, or having the RFID device mounted in a ring or other jewelery. To the poster that suggested that you could mount it in an earing hole, The read distances for the implantable devices is typicaly less than 3" and you would look funny putting you ear to every lock. The RFID devices are a chip with a small copper winding for an antenna encapsulated in a glass tube I dont think it would explode in an MRI but there is enough airspace between the glass and the tag itself that it is easily crushed.