In the above progression, the key of C major (with seven sharps) may be more conveniently written as the harmonically equivalent key D major (with five flats), and likewise C major (with seven flats) may be more conveniently written as B major (with five sharps). Nonetheless, it is possible to extend the order of sharp keys yet further, through C→G→D→A→E→B→F→C, adding the double-sharped notes F, C, G, D, A, E and finally B, and similarly for the flat keys from C major to C major, but with progressively decreasing convenience and usage.