Sisters Of Oz is the name Frank Peterson
gave to the two female vocalists featured on Sadisfaction.
Despite the name, this female duo are not actual sisters. The dark-haired
Susana Espelleta sings most of the lead
vocals for the verses, while blonde Birgit Freud provides harmony
during the choruses. As The Sisters Of Oz, they featured on only one
other album: Sarah Brightman's Dive.