The Richter-tuned harmonica, or 10-hole harmonica (in Asia) or blues harp (in America), is the most widely known type of harmonica. It is a variety of diatonic harmonica, with ten holes which offer the player 19 notes (10 holes times a draw and a blow for each hole minus one repeated note) in a three octave range. The standard diatonic harmonica is designed to allow a player to play chords and melody in a single key.