We can't forget to work the Back of our Shoulders. Target your rear delts with these,
High Cable Rear Delt Flyes.
You don't need an attachment for this one. The machine should have a little rubber like ball already hooked on that you will hold onto during the move. Adjust the cable so your hands are higher than your head to start. You will grab the LEFT pulley with your RIGHT hand and the RIGHT pulley with your LEFT hand. Crossing the cables in front of you.
Keeping your arms straight, pull the cables back and outward. Then slowly resist the cables on the way back to the starting position. That's it! This is my favorite exercise for the rear delts.
Second Fave: Reverse Flyes on an Inclined Bench
Third Fave: Seated Bent Over Reverse Fly