Ok, thanks much 5, Mike and moorea. Anyone know a machinist who makes spacers for these to hide the gap when having to use an adapter? I actually have a brass spacer coming from someone for my buzz, but he is busy and I don't want to ask him to make me for one for my infinity. He has/had a buzz and offered to make them anyway for some of us. I want to be able to use 510 carto's too and there is always a gap with a connection. My current infinity is a 901 connection and I haven't found a decent 901 carto out there. I always have to use an adapter. Hence....gap.