Optimize your drawing and calligraphy sessions with this set of 4 black ink refills from Pentel, designed for the Pocket Brush Pen GFKPN. Made specifically for this industry-leading brush pen, these cartridges deliver a smooth, consistent ink flow for precise, expressive lines. The rich black ink is ideal for calligraphy, sketching, illustration, and inking artwork. Easy to replace, these refills extend the life of your Pentel brush pen while ensuring professional-quality performance every time. An essential accessory for artists, illustrators, and calligraphers seeking reliability, control, and high-quality results.