In 1921 a Parker salesman requested a few Jack Knife Safety pens made in the large size and in orange hard rubber. This material is more fragile than Black Rubber and had not proven satisfactory for slip cap pens. Parker had plenty of material so the pens were produced and the salesman took them on his next trip. The pens sold great and the salesman returned with a number of orders. Soon the pen had a new name and the Duofold was born.

These are great pens. Durable, attractive, great writers. easy to use, what else can you ask for. They come in a number of colors and many variations. There are literally hundreds of different pens. The first were large and straight. This later changed to a modified streamlined version that became obsolete in 1933 with the introduction of the Vacumatic. The name was also used on less expensive lines like the stripped Duofolds of the 1940's.

These are very durable pens but they do have several common problems. The Hard rubber models frequently have cracks in the cap lips. The addition of cap bands helped but did not eliminate the problem in these pens. The earlier plastic pens have discoloration problems that is commonly associated with the first plastics. It is most prevalent in Jade Green pens and the Moderne colors. but it also affects most of the others. These pens usually have brassing on the sides of the ball on the clip. It is a high point and the gold wears off very fast. Pressure bars are often bent or broken. They are easily replaced and suitable parts are available.