For all levels. Here we have a typical minor blues in all 12 keys. Few chord progressions offer the freedom and variety of expression found in the minor blues progression. Great players have all approached this chord progression in a variety of ways; from attacking each chord vertically in its pure form to playing horizontally across the progression, (usually with a blues or minor pentatonic scale) to taking all or part of the changes totally harmonically "out". A perfect practise set for all.