Enigma Machine, I need help!

[sparkz_alot]

Indeed, at first I thought that the rings tripped after 26, but after further reading realized that there are 'tabs' on the rotor ring (for the Wehrmacht machine), in fact several, which does the actual tripping. The other thing that still has me confused, is the 'key', which was transmitted in the header of the message as a five letter group, the first two letters could be gibberish, but the last 3 were the 'key' and were sent in the clear. Of course, the one time page I was looking at is from 1944, after the Enigma I, and I can't find any info as to what the 'key' was used for. Perhaps the Wehrmacht switched from a 'set' reflector to an adjustable one?  If so, it would have added another level of security I suppose.