Uni-ball one is a brand new gel pen released by Uni on 2/26/2020. The pen comes with a newly developed Uni-ball One Ink, which is a darker and more vivid gel ink. Uni-ball One Ink uses pigment based ink with larger particles, which is less likely to be fully absorbed below the paper surface, thus creating a more vivid ink color. The ink dries fast, and writes smoothly similar to other Uni-ball gel pens such as Signo. The pen comes with a simple design, and a new color indication on the top of the pen. It also has a stronger metallic wire clip similar to therecently releasedJetstream Edge. 0.5mm Also available in 0.38mm Uni-ball One Black, Blue, Red refills available here