Gravitas produces their own nibs which will fit any pen with Jowo #6 threads. I have three Gravitas pens and all the nibs I have run broad and wet compared to typical western nibs, but I've heard others say theirs run dry, so it may be that there's some variation there. Every one I've tried writes well, though. They're all very smooth, which I like in a nib. The feedback is minimal and depends on the paper.
I've really enjoyed writing with this pen over the past month. I reach for it often. I'm finding that I want to keep all my Gravitas pens perpetually inked, which could be a problem if I keep acquiring them, which I certainly hope I do. The brand is taking over my pen case. That is not a complaint.
The Gravitas Polycarbonate Big Dropper sells for 95 Euros, which is pretty much equivalent to the U.S. dollar at the time of writing. That price is ridiculously good. It's too low, frankly. There's a pocket-size version for the same price, which I'll need, especially if the color tinting becomes available. Just be cautious browsing the Gravitas site, because everything is as awesome as it looks and you might be overcome with temptation. Meeting adjourned.
(Gravitas Pens provided this product at no charge to The Pen Addict for review purposes.)