From 1924 thru 1932 Parker produced mechanical pencils in the Duofold Flattop line (1924 thru 1929) followed by the Duofold Streamline line (1929 thru 1932). I'm showing today a small group of these pencils featuring the Parker named 'Mandarin Yellow' color. The Flattop models are pictured on the left and Streamlines on the right. The pencil 4th from the left is a transitional piece designed to help bridge the gap between old (Flattop), and new (Streamline). It had a very short life. The Parker Mandarin Yellow color began production in 1927. Other colors of both models were also produced during 1924 - 1932. For a size comparison, the Senior Flattop is 5 1/2 inches long. Matching fountain pens were also produced.