20 assorted colour staedtler triplus fine liner with superfine metal clad tip that has an ergonomic triangular barrel for effortless fatigue free writing these fine liner pens are dry safe which means they can be left uncapped for days without drying up they are also airplane safe meaning they have an automatic pressure equalisation which prevents pen leakage while on board aircraft although with their water based ink the colour washes out of most textiles line width approx 03 mm