3k refers to fiber count. 3000 woven or possibly filament wound. If I'm not mistaken all the lower end tubes utilize woven sheets.
Higher the K count, better the shaft, supposedly. More rigidity, power transfer, all that good stuff.
I have 2 custom CF shafts that were made for me that are 15k and 18k, respectively. You don't want to go over a certain k count from what I've been told.
There's a sweet spot??

What does that mean for me?? I have no fricken clue!!

They play well, for CF.
I believe Mezz uses 15 to 18k Filament wound tubes. Somebody correct me if I'm wrong, please.
That's going to be a quality shaft bro.
Vince uses 15k in his hybrids bcuz he says 18 is too rigid for his purposes, If I understood him correctly. Too rigid and brittle. You want a slight amount of flex. That's a given.
Vince also installs a tuned Damper, a proprietary ferrule material, and foam densities and vacuum pockets and

.
Both Vince and Jaden were literal treasure troves of information in regards to CF, shaft specs, playability, deflection, tuning, feedback, as well as the science behind it all and where this was headed.
I've had the privilege of speaking with both of these guys and I strongly suggest giving one or the other a call. Eye opening experience for me, to say the least.

It's my opinion that these new Hybrid- type shafts will be the end all in performance for quite some time. Obviously there will be tweaks and additions and mutations offered elsewhere. Nature of the bizz.
Plain ol CF will always have devotees, but every manufacturer out there has something along the lines of one of these hybrids in the works at present.
Coming generation of shafts is my guess.
Inexpensive CF tubes with a hollow section in the foam under the ferrule or vault plate, perhaps a CF rod inside extending 4" or 5", or all the way to the joint. 'Tuning' is becoming a 'thing' w these new shafts.
A custom tuned hybrid made for my style of play is something I never thot I would see. Now I have 2 and 2 more on the way. Each shaft has a different damper, Vince is experimenting with the types of foam and their densities and every shaft has been tuned for the precise hit I enjoy. How he manages that is anyone's guess.
Above my pay grade, that's for sure.
Vince @ 610 - 605 - 7318.
Jaden @ 480 - 290 - 0274