This exercise primarily develops the back of the deltoid muscle and the sublime muscles located on the upper back.
Hold dumbbells in both hands then take the attack position and bend forward your torso. Pay attention that your back should be straight. Lift the dumbbells to the side while you try to close your shoulder blades. At the highest point of the motion hold the dumbbells in the same position for a short while then place them back to the starting position and repeat the exercise. The exercise shall be performed with slightly bent elbows and wrists, this way you can reach a much better tension on your back and deltoid muscles. You can perform this exercise alternating your arms.