The chord wheel adopts guitar number system in music , which can identify each chord in a key by a number, applying the chords number system to the fretboard. Easy to master the chord music . This melody tool contains 72 most commonly used chord charts in12 keys. And turn the circle platter you can clearly see the chords fingerings charts in each key and their corresponding scale degrees (from I to VII). The back of the music transpose tool wheel with 36 seventh chord fingerings, which are major, minor, dominant 7th chords, makes the chord colorful. The front side contains the major triads, minor triads and half diminished sevenths. After practicing fingering and chord for a long time, you'll be to discover patterns, easily change keys, chord progressions, compose songs and even derive fingerings! Colour:Black+wood Material:Aluminum alloy + wood type: without base Package Contents: 1 x Guitar Chord dics Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.