Size 3 tip tops?
So I was planning on buying some 4pc 9'0'' 7wt blanks from Anglers Roost. I reached out to John who runs the place to ask the butt section OD and tip top OD so I could get the appropriate winding checks and tip top. He then told me that the tip top was a 3.0. After a few back and forth emails to confirm whether he was telling me it was 3.0mm or Size #3.0, he confidently told me that it was a size #3.0. The problem is, I don't think they make size 3.0. I can't find any tip tops that go below size #3.5, and I assume those would be for UL rods.
I'm completely new to rod building but I feel like I'm being misled. Thoughts anyone?