Hi Mark
these are designed to hook on the fretboard so might be a bit of a gimmick but they could also stand alone.
It's surprising how we get sucked in to buying stuff we thought we needed then find they quickly lose their purpose.
GT has the chord finder in the toolbox. Even if you just draw yourself one a day on some blank A5 chords you will quickly gather what you need and then only what you need.
Plus writing them out is another means of inputting data in to our little grey/gray cells
I always thought they would be handy for laying out some chord progressions on the music stand, either as common progressions but also as shuffling to give a few more random progressions while still using the common chords
Dave L
