Limited Edition 20 + 6 Pack: Triplus Fineliner Pens, 0.3mm, Metal Clad Tip, 26/PK (20 + 6 Neon Colors), Assorted. Staedtler Triplus Color marker and pen is acid-free with water-based ink and ideal for drawing, coloring in the classroom or adult coloring books. Staedtler Triplus Color marker and pen features triangular barrel for fatigue-free writing and the fineliner pen features line width of approximately 0.3 mm. Marker contains dry Safe ink and can be left uncapped for days without drying up.