The Uni Air Micro Liquid Ink Rollerball Pen in Blue is a smooth and strong liquid ink rollerball with a 0.5mm tip, ideal for precise, sharp and detailed work. The Micro Air pen is fade-proof, waterproof & smooth and the super ink hellos to protect against fraud. The pressure on the pen can determine the thickness of the line your desire. Uni-ball and uni are brands of pens and pencils, made by the Mitsubishi Pencil Company Limited of Japan. The brands currently have several lines of pens it's popularity has continued to grow, making it one of the world's most popular rollerball pens.