The Kaweco midnight blue 50ml fountain pen ink refill offers a sophisticated dark navy blue shade with excellent line definition. The 50ml glass inkwell features an airtight seal and stable design for safe refilling of writing instruments with a plunger converter. Its German-formulated ink provides quick drying with great opacity and lightfastness, without bleeding through to the other side of the paper. The formal elegance of midnight blue is perfect for executives, meeting minutes, and reports that require a distinctive and understated presence.