Mitsubishi uni-ball ZENTO Refill – Black, 0.5 mm

The UBRZ05 is the replacement refill for the uni-ball ZENTO pen series, carrying the same ZENTO ink technology that makes the pen worth coming back to. At the core of the formula is a POA (polyoxyalkylene) surfactant — a molecular layer that sits between the writing ball and the paper surface, reducing friction by approximately 40% compared to conventional water-based rollerball refills. The result is a writing feel that is noticeably softer and smoother without sacrificing control or line precision.

The ink is water-based and pigment-based, which gives it a different character from most gel refills. The pigment particles settle on the paper surface rather than seeping into the fibres, producing a high-contrast black line with good resistance to water and light once dry. Attracting particles in the formula also draw the ink together as it lands on the page, minimising feathering and bleed-through — even on thinner papers. It dries quickly enough to be practical for left-handed writers.

The refill is designed specifically for the uni-ball ZENTO range and is compatible with the ZENTO Standard, Flow, and Signature models. Features

• ZENTO ink with POA surfactant — approx. 40% less friction than conventional water-based rollerballs
• Water-based pigment formula — rich, high-contrast black line
• Attracting particles minimise feathering and bleed-through for crisp, clean lines
  
• Quick-drying — suitable for left-handed writers
• Compatible with uni-ball ZENTO Standard, Flow, and Signature models
• Tip size: 0.5 mm
• Made in Japan

See all Mitsubishi - uni items