STARTING POSITION:
You need to place a bench to do the exercise. Select the appropriate weight of the dumbbell. Place the right leg on top of the end of the bench and your right hand on the other end of the bench for support. Your upper body should be parallel to the floor. Contract your pelvic floor and core while keeping your chest facing the floor. Grab one dumbbell with your left hand using a neutral grip (palm of the hand toward your torso).
MOVEMENT:
With a pendular movements, move the dumbbell to all the directions. Repeat the movement for the specified amount of repetitions and then switch sides and repeat with the other arm.
TIPS: The exercise key is quality over quantity. The trick is to perform the exercise using proper form.