The Uni-Ball Signo Fine Gel Pen contains pigment ink to ensure your writing is bright and vivid. The ink is water proof and acid-free to ensure your markings are long lasting. It produces a line width of 0.7 mm for everyday writing. It's perfect for writing on paper, card and more. Each pen contains acid-free gel ink. Each cap colour matches the ink colour for easy identification. This pen contains orange ink.