This exercise is a slightly different take on the
lying down skull crusher. As the position of your hands are
different it works the long head of your triceps more
effectively.
1. Lie down on the bench with the pulley below your head height so
it gives your triceps a good stretch at the bottom of the
bottom. Face your palms over the bar (ie facing down towards
you) rather than under and facing away like in most tricep
extension exercise.
2. Ideally you should have a training partner bring the bar to you
as it could be awkward for you to grab the bar yourself. Then
start in the flexed position with the bar just behind your head,
then 'pull' the bar straight up working your triceps.