The TWSBI Kai is the third installment in the series ofTWSBI’s acrylic tortoise material pensthat have a small ink window near the grip section, and are paired with a rose gold trim.

Released in 2021 and earlier, the Draco and Aurora were the Kai’s predecessor as a limited run piston filling fountain pen in TWSBI’slimited “Classic” model.

TheKaiis fitted with a #5 size nib, the same nib used on TWSBI’s Diamond 580. It comes with a benchmark piston ink-filling mechanism, and the nib is smooth with a little feedback. The Kai fountain pen is only available in nib sizes EF, F, M, and B – unavailable in 1.1 Stub.

Note: This pen is post-able, but theTWSBIdoes not recommend it if you are worried about potentially scratching the barrel of your pen.

• Nib: Size #5
• Cap Type: Screw-cap
• Compatible inks & refills: Bottled inks
• Filling Mechanism: Piston
• Nib Material: Steel
• Diameter: 0.52″
• Capped Length: 5.55″
• Max Ink Capacity: 1.98ml
• Nib set
• TWSBI Diamond Ink Bottle

View allTWSBI products

About TWSBI:

TWSBI (San Wen Tong) is one of our earliest collection even before the store. TWSBI started as an OEM manufacturer for different western brands, and around 2009, they decided to start their own brand. With 50 years of experience in pen making, they took to fountain pen forums and gather users feedback. It was said that Pelican M800 was the model they were inspired. Most of their pens are transparent, so its really fun to see the ink color and it lasts for a very long time.

The name (San Wen Tong) comes from the Hall of the Three Rare Treasures, created by Emperor Qianlong as a memorial to three great masterpieces of Chinese calligraphy. The initials of the name San Wen Tong was reversed and thus turned into “TWS”. The last letters “Bi” was added with its literal meaning of “writing instruments” in Chinese. Thus combining the two segments, creating TWSBI.