uni-ball Air Rollerball Pen, 0.7 mm, Blue Ink, Dozen Sold as 1 Dozen. Uniquely designed hybrid tip allows free flowing ink to glide smoothly across the paper. Innovative Hybrid Tip adjusts to individual writing styles by delivering variable line widths at any angle. Writes bold like a felt tip marker and smooth like a rollerball. Variable ink laydown based on hand pressure.