The 4 colours fluo is a new member of the family which offers you 3 different colours of ink in the same pen aswell as an underliner letting you switch between them as your work dictates so you can efficiently complete your writing tasks the wide flourescent barrel contains 4 retractable points that write in black blue red amp yellow the 10mm points write with an elegant 04mm line width and the underliner has a 16mm tip with a writing line width of 042mm making this a great versati