1-7/16" litho reads "51/It's Here/Ask Me. The Parker “51” was a very expensive pen, even the basic model cost $12.50 while the top of the line set was $80.00, equivalent to $949.11 in 2000 dollars. Development of the pen was complete in 1939 so because that was the 51st year of the company’s existence, the pen was dubbed the “Parker 51.” This button was likely worn by company salesmen in 1939. However, sales were slow coming out of the Depression so a sales contest was devised lasting six weeks between May and June of 1941. The top prizes were 2 Cadillac's and over $7,000 in cash. All salespersons received a button reading "Parker 51 Club" to be worn during the contest. Couple of small 1/16" white scratches. VF. Rare.