This workout works on your middle fiber of trapezius. This workout is not done in most of the gyms. But if you want to develop your trapezius then you should add this work out to your chart.
You have to do it on incline bench, get yourself on prone position and grip the dumbbell. Your height must be sufficient enough so that dumbbell does not touch the ground. Now take shoulder upwards and bring it down slowly. Exhale while going up and inhale while going down.