The single-arm dumbbell arc row is an exercise for building the latissimus dorsi, or lat, muscles of the back. This variation has more of an arcing shape than the traditional single-arm dumbbell row, which may increase the mind-muscle connection and hit the back from a different angle. You probably won't be able to go as heavy on this as on a traditional row.
Builds bigger lats and upper back
Allows you to focus on one lat at time
Greater range of motion than traditional dumbbell rows