Okay, y'all inspired me. I've read several of the discussions about flashbulbs and decided to dig out the Rolleiflash that came with my 3.5E "beater". The only description I've seen (on marriotworld.com) of which bulbs can be used reads, "metal base (Swan, M2) and baseless (European all-glass bulbs)." Which other bulb sizes can this thing use? M3? Press 25? 25? From what I can find on flashbulbs.com there are "screw base", "bayonet base", and "miniature bayonet base." How do I know which will fit before I try to snag some on eBay?