Leave the cap off your fountain pen? Never—until now. If you’ve ever inadvertently left the cap off your fountain pen for a long period of time—and how many of us haven’t?—you know what a nuisance it can be. If only the ink wouldn’t dry so quickly! Private Reserve Infinity ECO (Extended Cap Off) Ink solves that problem—it's a breakthrough in fountain pen ink technology and truly a game changer for fountain pen users. Private Reserve's exclusive ink formula allows a fountain pen writer to leave the pen capless for a long, long period of time. In fact, if you continue to use the pen intermittently, you could theoretically leave the cap off forever.