This KOKUYO rollerball ink combination is designed to extend the life of your fountain pens with low-viscosity ink. The 0.5mm tip provides precise detail, ideal for detailed writing and sketching. Compatible with the WP-F200 series and other KOKUYO rollerball pens. The sturdy steel and plastic cartridge ensures a smooth, uninterrupted ink flow. Available in different colors to suit your preferences. Tip: 0.5mm Ink: Low Viscosity Compatibility: WP-F200 series Cartridge length: approx. 106mm Cartridge material: Steel and plastic Ink color: Blue-Black Country of origin: Japan