The garmon (, from , cognate of English harmonica), commonly called garmoshka, is a kind of Russian button accordion, a free-reed wind instrument. A garmon has two rows of buttons on the right side, which play the notes of a diatonic scale, and at least two rows of buttons on the left side, which play the primary chords in the key of the instrument as well as its relative harmonic minor key. Many instruments have additional right-hand buttons with useful accidental notes, additional left-hand chords for playing in related keys, and a row of free-bass buttons, to facilitate playing of bass melodies. The term "Garmon" means overcomer, winner or "noble" believed epistemologically to derive from the term for "blue" which nobility wore. It is believed perhaps Russian aristocratic, tzars and or royal leadership had garmons played in their courts. The garmons can be of two major classes: unisonoric, meaning that each button plays the same note or chord when the bellows is being expanded as it does when compressed; and bisonoric, in which the note depends on the direction of the bellowswork. Examples of unisonoric type are (, after Livny, Oryol Oblast), (, 'chromatic'), Tula accordion (, after Tula) and (, 'Italian') Beside Russian folk music, the garmon is an important musical instrument for Caucasian (Ossetian, Georgian, Cherkess, etc.) and Mari people in the Volga and Ural regions, and in Slovenian music. It is also used in popular music. Keyboard arrangement Although reduced and expanded versions are widely available, the standard arrangement (known as "25 × 25") is as follows: 25 treble buttons in two rows: three diatonic octaves plus three accidentals. There are versions with 27 treble buttons adding 2 more accidentals, and versions with 29 treble buttons adding 2 more high notes also exist. 25 bass buttons in three rows: two rows of eight buttons, with bass notes and chords; one free-bass row. Right hand The treble keyboard is arranged so that a scale may be played by alternating between the two rows. The low and high octaves have identical fingering, while the middle octave differs. The three accidental notes are arranged so as to mirror the position of the left-hand chords that contain them. Left hand The bass keyboard is arranged so that the principal chords for the major key are in the outer row, placed in circle of fifths order; the principal chords for the harmonic