Muscles: Back, Shoulders
Attach the pulley system in the upper position. Insert strap.
Stand in a hip-width, stable position at a slight angle to the device. Grasp the loops of the strap with your hands. Choose a distance to the device so that there is already tension on the pulley when you're in an upright position and the arms are stretched.
Pull your hands to the side of your ears. In the final position, keep the upper arms at a right angle to the torso. Pull shoulder blades down
You can vary between upper and under grip.