Printed on the bottom of the felt (in modern Zippos, not on older models) are the words, "LIFT TO FILL," to indicate one must lift the felt away from the "cotton" in order to refuel it.
Opening the top lid produces an easily recognizable "clink" sound for which Zippo lighters are known, and a different but similarly recognizable "clunk" when the lighter is closed. From 1966 until 1973 the year code was denoted by combinations of vertical lines.
Since its inception Zippo Lighters have been almost exclusively manufactured in the United States, with the exception of those manufactured in Niagara, Canada (an operation that has since been shut down). Blaisdell founded Zippo Manufacturing Company in 1932, and produced the first Zippo lighter in early 1933, being inspired by an Austrian cigarette lighter of similar design made by IMCO.
Zippo lighters became popular in the United States military, especially during World War II—when, as the company's web site says, Zippo "ceased production of lighters for consumer markets and dedicated all manufacturing to the US military".
It also contains a tube that holds a short, cylindrical flint.
The tube has an interior spring and exterior cap-screw that keeps the flint in constant contact with the exterior flint-wheel.