Dumbbell one arm reverse fly (with support)

Sit on a bench with your feet flat on the ground and your back straight. Hold a dumbbell in one hand with your palm facing inwards. Lean forward and place your free hand on the bench for support. Keep your arm slightly bent and raise it out to the side until it is parallel to the ground. Pause for a moment at the top, then slowly lower your arm back down to the starting position. Repeat for the desired number of repetitions, then switch arms.