Featuring a German engineered, ultra-smooth tip for the absolute best writing experience, the Schneider One Hybrid C 0.5mm pen has an incredible Super Flow System that provides for consistent ink flow. The One Hybrid C 0.5mm features an advanced liquid ink regulator which aides in compensation for air pressure fluctuations and provides a reliable ink flow from start to finish. The ink is waterproof and held in large ink reservoir with a visible level indicator. Use every drop of ink in your Schneider One Hybrid C!