First things first, i am aware (you should be as well) that each angle isn't specified to only that muscle part. All angles that involve a press work the entire chest, except for maybe shoulder press. each different angle shows you what you can focus more on but still work the entire chest. Angle Breakdown: Upper chest(30°-60°) Shoulders(90°) Lower chest(-10°-(-35°) Middle/All Chest(0°)