These Cello My gel pen has waterproof dark ink. The size of the nib or pen tip is 0.5mm. Cello My gel pens are water resistant, and are not washed away by water once the ink has dried. These writing gel pen makes you feel different about writing. ItâÂÂs stylish, comfortable,durable and ideal for everyday use. Benifits:- Its light weight body enables student to write for long time without pressure on fingers and wrist .Due to its smooth writing, quick drying, good color fastness and low cost, it has become a popular modern writing instrument . Gel pens always deliver an easy flow of ink which makes them quite user friendly. Specification:| Brand: Cello| Type: Gel Pen | Material: Plastic |Tip: Swiss Metal 0.5 mm Nickle Silver|Ink Color: Black| Package Content: Pack Of 20 | Uses: My gel pen mostly uses during exams by students.