3oz (90ml) glass bottle of Noodler's Blue Ghost invisible fountain pen ink, which glows under UV light. Noodler's inks are handcrafted, so there may be slight color and glow intensity variations from batch to batch.

Note: As this ink is virtually transparent, you may be able to see some particles that would be indistinguishable within opaque inks. We’re told that these particles are normal with this ink.