Uni-Ball Signo Gel Grip Medium Tip Pen Blue Triple Blister Pack, Pack of 6. The best selling Uni-Ball Signo Gel Grip Rollerball pen contains uni Super ink that is tamperproof and fade and water resistant. Featuring a rubber grip, this pen ensures a smooth and comfortable writing experience. Each retail pack contains 3 blue pens with a medium tip to write a neat 0.4mm line. The see-through barrel allows the user to view the ink level during use.