Uni-Ball Grip Fine Rollerball Pen UB-247 0.5mm Line Black Ink - Pack of 12 The Uni-Ball UB-247 is a good value liquid ink rollerball with all the quality Uni features. Stainless-steel tip; tungsten-carbide ball; waterproof and fade-resistant pigment ink. Comfortable rubber grip and metal clip. 0.7mm ball writes a 0.5mm line. Black ink - pack of 12.