The [[lever filler]] is probably the [[filling system]] most common among vintage pens (and has also been used, as a form of revival, by some modern manufacturers). Introduced massively to the market in 1912 by [[Sheaffer]], who has always proclaimed its invention, it has been produced in countless variations and versions, many of which, often technically inferior, have been created only to circumvent the patent ({{Cite patent|US|896861}}) that covered the invention of ''Walter Sheaffer'' that originated in 1908. | The [[lever filler]] is probably the [[filling system]] most common among vintage pens (and has also been used, as a form of revival, by some modern manufacturers). Introduced massively to the market in 1912 by [[Sheaffer]], who has always proclaimed its invention, it has been produced in countless variations and versions, many of which, often technically inferior, have been created only to circumvent the patent ({{Cite patent|US|896861}}) that covered the invention of ''Walter Sheaffer'' that originated in 1908. |