The patented airplane-safe technology prevents leakage on flights. Features Uni-Super Ink that helps prevent against check and document fraud. Fade-proof, acid-free waterproof ink provides permanence for important documents. Transparent barrel window shows when you're running low on ink. Airplane-safe ink technology. Features Uni-Super Ink that helps prevent against check and document fraud. Fade-proof and waterproof ink. Visible ink supply.