Choir Rocks! Mercy, originally performed by Duffy, is arranged for upper voices with piano accompaniment by Ben Perry. 
Choir Rocks! Series offers flexible arrangements of contemporary pop hits. All pieces are written for soprano and alto, with an optional third part of limited range for baritone or low alto with straightforward piano accompaniments perfect for the amateur pianist. Also includes chord symbols for the addition of guitar, bass, and drums for a more electric performance.