The Sportster is a line of motorcycles produced continuously since 1957 by the Harley-Davidson Motor Company. Sportster models are designated in Harley-Davidson's product code by beginning with "XL". In 1952, the predecessors to the Sportster, the Model K Sport and Sport Solo motorcycles, were introduced. These models K, KK, KH, and KHK of 1952–1956 are not always considered to be Sportsters, but are definitely the precursors and inspiration for the line.