The 12 bar blues progression, and variations on its theme, is the basis for all blues, some jazz, and many rock & roll songs. It uses all dominate 7th chords.
Ab Major has 4 flats: Bb, Eb, Ab, and Db. The relative minor of Ab Major is F minor. Ab Major is tonally identical to and can be referred to as G# Major.
The Boss RC-2 Loop Station is packed with fun stuff. It allows an instrumentalist to record and layer loops naturally or to a set-tempo metronome or drum track.
C major uses no sharps or flats. The chords in this key are: C maj, D min, E min, F maj, G maj, A min, B diminished. The relative minor of C Major is A minor.