50 and 80-90mm enlarging lenses need no cone.
You can print up to 6x7 maybe 6x9 depending.
The longer cones are for 4x5 with either a 135mm or longer lens.
I had an old wollensack enlarging raptor that came with my D2 and it was something like 142mm or 152mm or some odd focal length. I think that lens needed the longest cone.