When properly adjusted (and assuming the pack is the right torso length),and in conjunction with a load-carrying hipbelt and some sort of frame, "load lifters" or as they are also called, "lifter straps", allow you to take pressure off the top of your shoulders. You accomplish this by tightening the load lifters and also slightly loosening the shoulder straps. This combination of adjustments means that you now have tension between the top of the lifter strap and the bottom of the shoulder strap, rather than tension between the bottom of the shoulder strap and the point where the shoulder strap is attached to the pack. Thus, you have no pressure, or reduced pressure, on the top of your shoulders, and some increase of pressure on the front of your shoulders. You also hold the pack more snugly to your back - good for vigorous activities like scrambling or skiing. they don't work well without a frame,or if the frame is too short so that you can't get the lifter strap to run uphill from your shoulder to the pack.