The exercise is the same as the regular long pulley, but with a narrow grip:

Sit down, put your feet on the supporting points and grab the bar with a wide grip. Pull the weight with a rapid movement towards your belly button, not upper. Keep your arms and elbows during the movement close to your body. Your shoulders are pulled together. Let the weight slowly down till your arms are completely stretched.

El diagrama muestra los músculos más usados en este ejercicio