TWSBI Kai Fountain Pen

The TWSBI Kai Fountain Pen is a limited-edition release finished in a dark blue flecked acrylic resin with rose gold trim throughout — cap, clip, rings, and nib all carry the same warm metallic accent against the deep blue body. Like every TWSBI, it's built to be taken apart, cared for, and put back together, turning routine maintenance into part of the ownership experience rather than something to avoid.

The Kai uses TWSBI's benchmark piston ink-filling mechanism: a twist of the end knob draws ink straight from the bottle, no cartridge or converter required. An ink window along the barrel lets you see exactly how much ink remains at a glance. The rose gold nib is sized comparably to the TWSBI 580 nib, and every part of the pen is fully detachable for cleaning or servicing. Each pen ships with a wrench and silicone grease for long-term care — not needed on day one, but there when the pen eventually calls for it. Note that while the cap can physically post onto the back of the barrel, TWSBI recommends against it, as posting risks scratching the acrylic.

TWSBI is the in-house brand of Ta Shin Precision, a manufacturer with more than 40 years of experience producing pens — including for other brands — before launching under its own name. The name TWSBI combines "TWS," the reversed initials of "San Wen Tong" (Hall of Three Cultures), with "BI," meaning writing instrument.

Key Features

• Limited-edition dark blue flecked acrylic resin body with rose gold trim — will not be produced on an ongoing basis.
• Rose gold nib, clip, and rings, sized comparably to the TWSBI 580 nib.
• Available in Medium and Broad nib grades.
• Piston ink-filling mechanism — twist-fill directly from a bottle, no cartridge needed.
• Ink window for at-a-glance visibility of remaining ink level.
• Fully detachable design, built for disassembly, cleaning, and reassembly.
• Ships with a wrench and silicone grease for long-term maintenance.