Dumbbell one arm bench fly

Sit on a flat bench with a dumbbell in one hand, resting it on top of your thigh. Lie back on the bench, keeping the dumbbell pressed against your thigh. Using your free hand, help lift the dumbbell up to the starting position. Hold the dumbbell directly above your shoulder with your arm extended and palm facing inward. Lower the dumbbell out to the side in a wide arc, keeping a slight bend in your elbow. Pause when your arm is parallel to the ground, then reverse the movement and bring the dumbbell back to the starting position. Repeat for the desired number of repetitions, then switch arms and repeat.