uni-ball Vision Elite BLX Series Roller Ball Stick Pen, 0.8mm, Green/Black Sold as 1 Each. Patented airplane-safe technology prevents leakage on flights. uni-flowTM system delivers a smooth and steady flow of water-resistant ink, ensuring skip-free writing with a consistent color. Exclusive pigment-based ink forms an indelible bond with paper for intense coloration and document security.