I have a number of long keys, I would like to identify, they have square bows with the SG of sergeant and greenleaf, then a round shaft of about six inches with a lever tumbler lock bitting on the end, just before the bitting for the levers, the round shaft tapers down to a smaller diameter. the bitting appears to address 6 or 7 levers, but the whole blade of the key that they are cut from is small, the height of the bitting does not come to a quarter inch, but its length along the key shaft is about an inch.
I don't have the capability to put a photo up as these cafe machines restrict the down and up loading. perhaps someone has some information, I have looked at the SG site, and my guess is that these are no longer sold.