Gel pen, also known as ink pen, originated in Japan and is a novel writing tool popular in the world. Gel pen has the advantages of fountain pen and ballpoint pen, with comfortable writing feel, low ink viscosity and easy lubrication of added substances. The viscosity of writing medium is between water-based and oily, so it is smoother than ordinary oily ballpoint pen, and it is an upgraded product of oily ballpoint pen.

Neutral refill specification

Neutral refills are mainly divided into needle tube type and bullet type, in which the thickness of needle tube type refills is generally between 0.3 and 0.5, bullet type refills can be used for very thick refills, and the thickest ones can be above 1.2.

Classification of neutral refills

Neutral refills are mainly divided into bullet type and needle type, and needle type is divided into full needle tube and half needle tube. It can also be classified according to the color and structure of ink.