The ketone-based ink glides on smoothly and erases just as easily, and is low odour to ensure comfort when writing extensively. It features a strong acrylic tip that won't bend or retract into the barrel, even with heavy use. The chisel tip delivers a variable line thickness between 3. 7mm to 5. 5mm, perfect sketching diagrams or creating bold titles. Velleda drywipe markers are ideal for everyday office use, and are great for meetings and conferences. Can be used on any dry wipe surface and erased up to a few weeks later on quality white boards. Strong chisel nib won't bend or retract under pressure.