This pen can be considered a precursor to pressurized ballpoint pens that can be used in space. Because it's pressurized, you can write with it upside down or on wet paper. It has a U.S. flag on it to prevent rolling. The ink flows. The remaining amount is unknown. A ballpoint pen made for space, approved by NASA. Space Pen Bullet Chrome EF-400 Ballpoint Pen Type: Ballpoint pen Ink: Oil-based Features: Single color Body material: Metal #PressurizedBallpointPen #NASA #USA #ShortBarrel #ChromePlated #CapType #AmericanFlag #Space #StarsAndStripes