Overview Reviews Product Description Sei Boku blue black ink is a waterproof ink made of high quality material and is extra blue black. Product Videos Custom Field Product Reviews Write a Review Write a Review × Sailor Sailor Fountain Pen Pack Of 12 Seiboku Blue Black Pigment Ink Cartridges Rating * Select Rating 1 star (worst) 2 stars 3 stars (average) 4 stars 5 stars (best) Name Email * Review Subject * Comments *