I recently bought a grinder on eBay, and the seller threw in three portafilters for free (!), but he doesn't know what machines they came from. I have a La Pavoni PUB and a Conti, both commercial machines, and these portafilters don't fit either one. I then took them to a repair shop while on vacation in another city, and was told that they fit Faema-type and E61 groupheads. At least this is what I think he said. I didn't know all E61 groupheads used the same size portafilter. Is this true, or did I misunderstand something? Also, I took them to a local café where a friend of mine is a barista to see if they fit their machine, a Simonelli, and they didn't fit. Is this enough information for anyone to tell me what machines they will fit? Do I need to keep trying them out on other machines? I would like to keep them for when I get another machine, or sell them, but need to be able to tell potential buyers what machines they will fit. Any help or suggestions?

Photos of said portafilters would be helpful.

Well if they fit all E61 machines, then it's 58mm...right?

Yes, I could interchange all the portafilters of the E61 espresso machines I've used. The E61 groups are not necessarily identical (e.g., I've read about fitment problems with the internal valves), but they're close enough in most cases. Photos of said portafilters would still be helpful.