Sitting on a bench with your back well supported against the backrest. Position the bench so that the bar drops just in front of your face. Grasp the bar with your hands in pronation. Your back is well supported against the backrest, your elbows are on the outside and your forearms are perpendicular to the ground.
Unhook the bar and slowly bring it to the height of your chin. Contract your shoulders by pushing the load upwards. Stop the movement just before your arms are fully extended. Then return to the down position.