This is yet another tiny "Look a like" key project, a real sub miniature  The Boston Spark,  it uses the smallest bearings only 5mm Dia with a 1.5mm axle, there wasn't enough room for an ID tag so not sure about that, the total length of the key arm is 60mm, I think it really is about as small as I can make a fully adjustable working key, having at last reached my own limitations, but real fun to make, and it actually works quite well!! even had a couple of good contacts with it, although the arm earth clip tends to dampen the action in such a tiny key. Time to move on to something a bit bigger :)