12 Pack - Private Reserve Ink, Universal Fountain Pen Ink Cartridges Clear Case, Invincible Black Description Private Reserve fountain pen 12 pack cartridges are an excellent choice for your ink and represent one of the best International Ink Cartridges Standard Size available on the market. Invincible Black ( C49 ) ink is non-smearing neutral in pH and offers a great writing experience for your writing instrument. Features ? Neutral pH ? Non-clogging ? Smooth ink flow ? Water soluble ? High saturation ? Minimal feathering ? Premium Quality ? Normal spread ? Rich, vibrant fountain pen ink color ? 12 pack of cartridges per box ? Slim, hangable, and reusable clean plastic storage box ? Please note there might be slight variations of ink color compared to photos of color swatches. Technical Specs ? Color: Invincible Black ? Material: Plastic ? Collection: International Ink Cartridges Standard Size ? Universal size fountain pen ink cartridge ? Length: 1.5 inch / 38 mm (Single Ink Cartridge) ? Item Dimensions (L x W x H): 1.7 x 0.38 x 4.25 inches ? Excellent coverage