Below is the newly redesigned M-4 type collapsible shoulder stock from Bushmaster. The rear sling mount rotates up to 90 degrees to either side. The stock is very rigid and quiet. Notice the butt pad is wider and angled differently than the original style CAR stock below. This give an improved fit and feel.
Below is the stock CAR shoulder stock. This thing was made of plastic and rattled too much before it was glued into place.