Doubled die (also known as hub doubling) is a term in numismatics used to refer to a duplication of design elements on a working die created due to a misalignment of the die or hub during the hubbing process. Strength of the doubling can vary from very slight and isolated to extreme and widespread. The exact cause of the doubling can also vary, which is why a class system was created to outline the known and hypothesized causes. Doubled die varieties, when noticeable to the naked eye or occur in a popular coin series, are extremely popular with collectors and can be worth a large premium over the same coin without the doubling. The most popular doubled die variety would be the 1955 US cent doubled die which typically sells for over $1000 at auction. This term is commonly misspelled "double die." Classes of doubled dies Doubled dies are created when the hub imprints an additional, misaligned image onto a die. The many ways this misalignment of images can occur have been arranged into eight classes. This class system was created when United States mints used a multiple-squeeze hubbing method, meaning the working dies were intentionally hubbed multiple times to transfer a complete image. Many mints worldwide, including the United States, have since transitioned to a single-squeeze method, expecting the elimination of this hubbing error as only one hubbing is needed. However, the frequency of doubled dies actually increased with the new method. These new single-squeeze doubled dies have slightly different characteristics than ones from the previous method, leading to different opinions on whether the class system has to be revised or not. Some believe the single-squeeze doubled dies still fit in the existing system while others added a new ninth class for single-squeeze doubled dies. Class 1, Rotated A class I doubled die results when the die receives an additional hubbing that is misaligned in a clockwise or counterclockwise direction. Class 2, Distorted A class 2 doubled die results when the hub's design moves toward the rim between hubbings. Class 3, Design A class 3 doubled die results when a hub bearing a different design stamps a die bearing another design. Class 4, Offset A class 4 doubled die results when the die receives an additional hubbing that is misaligned in an offset direction. Class 5, Pivoted A class 5 doubled die results when the die receives an additional