Erasable Ballpoint Pen, 0.38mm FriXion FriXion 4 FriXion 4 4 Color Ballpoint Pen. 0.38mm is the ninnest lead diameter in the Friction series. It is convenient for you to write in small letters and color codes on your notebook, notebook, etc. Ink Color: Black, Red, Blue, Green Ink Type: Gel Ink Ball Diameter: 0.38mm Other colors are used in some images. Size: Height = Width = Width = 20mm Thickness = 13mm