Cable one arm decline chest fly

Attach a D-handle to a low pulley cable machine and set the bench to a decline angle. Lie down on the bench with your head towards the machine and grab the handle with your right hand. Extend your arm straight up above your chest, keeping a slight bend in your elbow. With a controlled motion, lower your arm out to the side until your hand is in line with your shoulder. Pause for a moment, then reverse the motion and bring your arm back to the starting position. Repeat for the desired number of repetitions, then switch to your left arm and repeat the exercise.