The True Rear Delt machine strengthens your shoulder muscles by developing your posterior deltoids. If you deal with upper back pain and constantly find yourself hunching and rounding your shoulders, the True Rear Delt machine can strengthen your rear deltoids to correct this problem and improve your posture! Compared to free weight exercises such as the bent over reverse fly, the True Rear Delt machine provides far more stability. Proper form is essential to getting all the benefits of the True Rear Delt machine.