The Jiandan Erasable Gel Ink Pen has a 0.5mm tip that produces a 0.5mm line thickness. It's filled with blue gel ink that's advertised as "Writes Smooth, Erases Clean, Quick Dry." The pen is designed with an erasable ink formula, letting you rub out mistakes easily. The packaging shows 12 pens in the box, each with a plastic barrel and a 0.5mm gel tip.