uni-ball Vision Elite Stick Roller Ball Pens, Bold Point, Black Ink, 2 Packs of 4- total of 8 Number of Items: 2 Packs of 4 Ideal for the business traveler--contains a vented refill so pen won't leak or explode due to a change in cabin pressure during flights Uni Super ink is specially formulated to become trapped in paper, helping prevent criminal check washing and other document alteration. Quick-drying, acid-free, archival-quality ink is fade- and water-resistant to last over time. Exclusive uni-flow ink system ensures a steady flow of waterproof, fade-resistant ink of consistent smoothness and color intensity down to the last drop.