The Grey Birch Bag Rider provides additional surface area and more stability to the rear of the Grey Birch folding stock chassis system. No modifications is needed to attach to your Grey Birch Folding Stock. If shooting precision matches or distance shooting is your thing, the bag rider may just be what you've been looking for. Simply bolt on and give your rifle the "bag punch" it deserves. FeaturesHigh Performance NylonDimensions: 5.6" L x 3.2" H x 0.7" W