Sensei Pigma Black Pens has Pigma's specialty ink that is permanent, pigmented, waterproof and archival. Ink will never bleed though even the thinnest paper because the pigment particles remain on its surface. The pen comes in four nib sizes for great variety of line types: .3mm ultra-fine tip , .4mm durable plastic tip, .6mm bullet fiber tip and a 1.0mm bold tip. The finer tips are good for facial expressions, lettering or detailing images, while the broader tips can create bold lines to cover large areas and add impact and drama.