So, the websites that claim that the BF-xx (often the BF-1B) is a "replacement" for the BF-3A are all liars. The only cap that fits the teleconverters that need the BF-3A actually is the BF-3A. Or at least that's what I'm finding out as I look and look and look for one. Anyone have an extra they want to sell? Anyone know where I can find one? Any non-nikon suppliers that make that particular size? It's gray, apparently they made it a different color because it look almost exactly like all the other body caps except it isn't exactly the right size so it doesn't fit unless you force it. And that's really not recommended.