Lie flat on a bench with a dumbbell in each hand, palms facing each other. Extend your arms straight up over your chest, with a slight bend in your elbows. Keeping a slight bend in your elbows, lower the dumbbells out to the sides in a wide arc until you feel a stretch in your chest. Pause for a moment, then reverse the movement and bring the dumbbells back to the starting position. Repeat for the desired number of repetitions.
GIF