The most common type of harmonica is the diatonic or Richter harmonica, named after Joseph Richter from Bohemia, a folk musician who developed this tuning system around 1825. These instruments are often generically referred to as Blues Harps, reflecting the popularity of the HOHNER model Blues Harp. The diatonic harmonica is a single voice instrument and usually has 10 channels, each with one blow and one draw note. It is mainly used in the blues, where the HOHNER Marine Band has played a vital role. The HOHNER Marine Band is the original blues harmonica and can be heard on virtually all recordings by blues legends such as Little Walter Jacobs, Sonny Boy Williamson I & II, Sonny Terry, Big Walter Horton and many more. Richter harmonicas are also frequently used in styles as diverse as pop, rock or country and, in recent years, increasingly in jazz. Due to their diatonic tonal layout, the player generally needs several instruments in different keys.