TWSBI Black fountain pen ink is a dark shade of black, and these cartridges come packaged as a box of 10. The TWSBI Red fountain pen ink cartridges have a standard international opening, but have a bigger girth and longer length than short standard international cartridges, so these will not fit other pens that accept short international cartridges.

Having trouble deciding between colors? Use our Ink Comparison Tool to quickly and easily view different colors side by side.

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