One Hybrid C 05 Rollerball Pen Cap model. Ink type: water-based ink, indelible. Refill design: hybrid cone tip for smooth writing, 0.5 mm, blue. Can be left open for a few days without drying out. Ink reservoir technology: free ink system. Pen design: plastic, ergonomically rubberised. Clip material: high-quality metal clip. Super flow system for even ink flow. Large ink supply with viewing window. Barrel colour: denim blue.