Demonstrator mechanical pencils were created by writing instrument makers to show the operations of their internal mechanisms. Cutouts and clear barrels accomplished the goal. Shown here are pencils from the 1920s into the late '50s. Salesmen might carry these around to retailers or retailers might show them to customers. They typically were not 'for sale' items. From left to right here are Sheaffer, Sheaffer, Pelikan, Wahl-Eversharp, Sheaffer, Sheaffer, Parker, Sheaffer, Eversharp, Wahl-Eversharp, Sheaffer, and Eversharp. Outside the box: Parker (above) and Eagle (below).