One-Arm Bent-Over Dumbbell Rear-Delt Raise (With Box)
Assume a split stance in front of a box or bench with your right leg forward, and place your right hand on top of the box. Grasp a weight in your left hand with your palm facing inward and your arm hanging straight down toward the floor. Keep your back straight as you lift the weight up and out to the side, leading the motion with your elbow, until it comes to about shoulder height. Slowly lower to the start. Complete all reps on one side, then switch.