23 ml drawing ink for technical pens. Single bottle available in black, blue, red, green, or white. Designed for easy refilling of Isograph-compatible technical pens and other reservoir-style drawing pens. Key benefits Reliable flow for precise lines: Smooth ink delivery helps maintain consistent line quality during detailed work. Practical size: 23 ml bottle provides multiple refills while remaining compact for a drawing kit or workstation. Simple refilling: Narrow-neck bottle and liquid consistency allow controlled filling without frequent interruptions. Color variety: Choose black, blue, red, green, or white to support color coding, highlights, and layered drawings. Versatile use: Suitable for technical drafting, illustration, mapmaking, and general ink drawing where pen refills are needed. Important attributes Function: Refill ink for technical and Isograph-compatible drawing pens. Compatibility: Intended for Isograph-style technical pens and other similar reservoir pens. Size: 23 ml per bottle, sold as one piece. Material: Liquid drawing ink formulated for pen use. Performance: Engineered for smooth application and dependable flow in technical pen nibs. Practical applications Architectural drafting: Refill technical pens for precise plan lines, detail work, and color-coded layers. Technical illustration and engineering diagrams: Maintain consistent ink flow across repetitive detail work and annotation. Illustration and visual notes: Use colored inks to separate elements, add emphasis, or create mixed-media sketches. Package content One 23 ml bottle of drawing ink in the selected color. Usage tips Follow your pen manufacturer recommendations for refilling procedures. Store upright and tightly closed when not in use to reduce evaporation. Test ink on scrap paper before use to confirm color and flow with your pen.