You know how to form chords theoretically, but if I ask you to play a D flat diminished seventh in second inversion, do you know how to play it instantly? You like to play from lead sheets or fake books but you need some more chord practise? If not, then this is the program for you! Especially if you don't have anyone to help you practise chords (i.e. they call out a chord and you play it) with.