This movement is used to target the rear head of the deltoid muscle. This is useful to isolate the muscle and the use of cables will ensure constant resistance throughout the movement.
For this movement you need to pulleys that are at the floor level. Grab the handle on the opposite side of the body. Next, bend over at the waist so that your torso is parallel to the floor. Make sure to keep your back straight and still throughout the movement. Next, with a slight bend in your elbows, pull the arms across the body and then straight up as far as you can. Make sure to feel a squeeze in rear deltoids. Next, lower the handles back to the starting position slowly and under control.
A slight bend in your elbows will allow you to really squeeze the muscles of your rear deltoid; do not lock your elbows.
This movement can be done with dumbbells, but the cables will provide constant resistance throughout the movement.