THE WASHER CLIP.
On May 24, 1916, Moore filed patent application US1,197,224 for what would become the famous Parker Washer clip. This improvement enabled the clip to be located at the extreme end of the cap, so the pen sat deeply and securely in the pocket with only a fraction of the cap protruding. It fitted elegantly, simply, and economically on the Jack Knife cap that Parker had been making; they seemed created for each other. This was perceived as a valuable customer benefit when most pocket clips were located halfway up the cap so that pen rode high in the pocket.
A significant benefit of the Moore Washer clip was military. Soldiers can’t have reflective metal on their persons because the enemy can target the reflection. The washer clip fits under the pocket flap of the military uniform, so the clip is not visible. Possibly because of this feature, Parker sold more pens to the Army for use in World War One than any of its competitors.
Moore voluntarily assigned his invention to the company, and in recognition of his devotion, George Parker paid him a royalty during the 17-year patent life.