Pigma Brush Pen Black Medium has a flexible nib for thin and thick brush lines. The extra durable, long-lasting and “memory” enhanced nib is made of MB, a tough nylon material. Its durable brush nibs respond instantly to changes in pressure or direction, giving a silky-smooth, accurate and consistent ink flow. The unique Sakura Pigma™ ink will not bleed through paper, is permanent, waterproof, fade resistant, quick drying and pH-neutral. Ideal for illustration, journaling, sketching, rubber-stamping and comic art. Available in other nib sizes and in a set.