The tenor guitar is a slightly smaller, four-string relative of the steel-string acoustic guitar or electric guitar. Gibson Guitar Company and C. F. Martin & Company initially developed the acoustic tenor guitar. The intent of this instrument was to enable players of the four-string tenor banjo to double on tenor guitar. As early as the late 1920s, the tenor guitar started to outpace the tenor banjo in popularity. The tenor guitar was first manufactured as a production instrument, starting in 1927, by the Gibson Guitar Company and C. F. Martin & Company, and continued to be manufactured by Gibson and Martin companies from the late 1920s until the 1970s. It is a very early production version tenor guitar. Lower-cost tenor guitars by makers such as Harmony, Regal, and Stella were produced in large numbers in the 1950s and 1960s, and are still widely available. Tenor guitars can be heard in country, western swing, jazz, contemporary folk, and pop music.