Vintage IBM Electrographic Mark Sensing Pencil Leads
One box with 125 units of leads.
The box marked Eberhard Faber contains 125 units of leads.
Diameter of a lead is 2mm.
Each lead is marked with inscription IBM - Electrographic.
"The Electrographic mark sensing leads were used with the now familiar fill-in-the-bubble test score sheets. These sheets, once filled out, could then be scanned into a Test Scoring Machine which could read the answers by sensing the electrical conductivity of the pencil lead. The test machines were withdrawn from the market in 1963 replaced by an optical recognition system".
Measurements of the box: 14cm/5.5" x 5cm/1.96" x 1.8cm/ 0.7".
Leads are in very good vintage condition - unused.
Box itself has few scratches and surface tears - it is in medium good vintage condition.
Protective paper inside the box is with some testing marks of the lead itself.