Vintage IBM Mark Sensing Pencil Leads Electrographic 35+ Pieces

IBM Mark Sensing Pencil Leads, specifically designed for electrographic mark sensing technology. These leads were used with IBM's mark sense technology for machine reading of human-made marks on documents like tests and utility bills. Purpose: Designed for use with IBM's mark sensing technology, allowing machines to read marks made by the pencils. Material: Made with electro graphite, a type of artificial graphite that is more conductive than standard pencil lead. Function: The graphite in the lead conducts electricity, enabling machines to detect the marks. Usage: Used for marking on specialized cards that could be read by machines for data processing.