For more than 40 years, standard black pens have cluttered the desks of thousands of federal employees, hung on a chain at post offices across the country and slipped into the pockets of countless military personnel. Yet few have realized that this government-issue pen has a history to rival that of any monument.

Blind workers assemble the pens in factories in Wisconsin and North Carolina under the brand name Skilcraft as part of a 72-year-old legislative mandate. The original 16-page specifications for the pen are still in force: It must be able to write continuously for a mile and in temperatures up to 160 degrees and down to 40 degrees below zero.

It has been used in war zones and gas stations, and was designed to fit undetected into U.S. military uniforms. According to company lore, the pen can stand in for a two-inch fuse and comes in handy during emergency tracheotomies.

"It's the Coca-Cola of ink pens," said Richard Oliver, operations manager at Industries of the Blind in North Carolina. "Everybody recognizes this pen."

The unassuming pen stamped with the words "SKILCRAFT U.S. GOVERNMENT" in white letters has endured despite quantum leaps in communications technology that have rendered lesser tools obsolete. Taking over from the fountain pen, it has withstood the advent of the rubberized "comfort grip" and the freely flowing gel ink, not to mention computers, instant messages and smartphones. The U.S. Postal Service alone orders 700,000 a year.