Apart from NOS, the only ones I have ever seen were EMGO, at the price in your link I would say the are Emgo. There a lots of Smaller Honda {175, 250, 350} Ignitions for sale on ebay, they are the same barrel as the 500, 550, 750 with slightly smaller wiring, same plug and all. You can have trouble with the smaller diameter wire burning out but that can be fixed with a relay to take load of the switch and you'll never have a problem again.. I have bought a couple and the diameter or gauge of the wiring is the only difference..