The Inverted Jenny (also known as an Upside Down Jenny or Jenny Invert) is a United States postage stamp first issued on May 10, 1918 in which the image of the Curtiss JN-4 airplane in the center of the design appears upside-down; it is probably the most famous error in American philately (stamp collecting). Only one pane of 100 of the invert stamps was ever found, making this error one of the most prized in all philately. A center-line block catalogs for $600,000, which is probably low; a single inverted Jenny was sold at a Robert A. Siegel auction in November 2007 for US $977,500.