Jacoby has Black V4 and Ultra Pro shafts with 19" pro taper. Is that the maximum for any company?
I have 4 Jacoby Ultra shafts. Two were purchased with 30" length and the standard 12.75 mm, and one was a 29" 12.75 mm.
Also have one 30" at 12.5 mm that I had them custom make at the 12.5 mm when they were building it. The three that I purchased at 12.75 mm, I have taken all of them down to basically match the 12.5 custom shaft I got from them.
While Jacoby advertises a 19" pro taper, and some think that means the shaft is the same diameter for that 19", that would not be even close to what it really is. It may be for carbon shafts, but not for wood, and seriously don't think you would want a wood shaft that does not taper up for the first 12"-19".
Their pro taper for the 12.5nmm shaft is, Ferrule-12.5 mm, 2"-12.6 mm, 4"-12.7 mm, 6"-12.92 mm, 8"-13.05 mm, 10"-13.11mm, 12"-13.18 mm, 14"-13.24 mm, 16"-13.66 mm
So while a pro taper, it still gets progressively larger and probably at the 19" area probably gets larger faster.