These pens have an ergonomic triangular barrel for relaxed and easy writing. The water-based ink washes out of most textiles. The pens are air plane-safe and the automatic pressure equalisation prevents the pens from leaking on board aircraft. The ink is dry safe which means that the pens can be left uncapped for days without drying up. They are dry-safe so they can be left uncapped for days without drying up and the waterbased ink washes out of most textiles.