Rotring Isograph Technical Pen, 0.18 mm Rotring Isograph high precision technical pen for drawing and lettering on tracing paper, vellum drawing paper and lineboard. The isograph has a refillable ink reservoir. Its innovative push-on sleeve makes for easy access to the ink helix for fast cleaning. The nib is stainless steel. Each pen is color coded by line width in compliance with ISO standards. Made by Rotring in Germany. Ink sold separately. Length: 4.9" (124 mm); Width at center of barrel: 0.44" (11 mm); Weight: 0.3 oz. (10 g) Additional Images: Cap screws on to protect nib Skyscraper artwork by artist Mark Lascelles Thornton using Rotring pens.