Flash pen means that the ink in the refill contains flash powder, and the writing font flashes under the light. According to the different colors of ink, you can write different colors of fonts, which will glow under the light, so it is also called sequined pen.

Pen is a common Chinese word, and "Yu" is the original word of "pen", which was first seen in Oracle Bone Inscriptions and pronounced as bǐ. Its original intention is to write with a soft writing instrument made of bamboo tube and animal hair.