"Rot ring" literally means red ring - which is still placed around the barrel of their pens today. The company's name was changed to Rotring in the early 70s to match the trademark.
Although stylographs never overtook fountain pens for use in writing, by 1953 the Rotring Rapidograph became the prototypical technical pen of its age. Its technology virtually replaced the ruling pen and greatly simplified technical drawing. Rapidographs are still made today, both by Rotring and by Koh-i-noor, its US subsidiary.
The advent in the 1990s of computer-aided design (CAD) saw the partial demise of the technical drawing pen. To combat this, Rotring diversified its range of graphic pens, pencils and markers.
In 2005 Rotring stopped shipping their products to the United States.