Branching from what Darryl said here A few years I did a 3 month survey recording lamps on Ebay trying to find out if blue hoods were from Kopsens (Sydney) and green hoods were Nettlefold (Melbourne) or visa versa. The results were quite conclusive from start to finish. About 95% of the time, blue hoods were Kopsen and green hoods were Nettlefold. Knowing that surveys are funny things and that the results on one day can be different to the next, I decided to do it again. Not for as long as the first time. I think it was only a couple of weeks. Again, the results were quite conclusive. However, the results were reversed. About 95% of the time, blue hoods were showing Nettlefold and green were showing Kopsen. Go figure.