Evolution Gun Works AR Bag Rider Rear Only Steel. You must remove the rear sling swivel. The insert from the rear bag rider then can be slid in to place and then secured with the screw from the sling swivel. Specifications for Evolution Gun Works AR Bag Rider Rear Only: Manufacturer: Evolution Gun Works Color: Silver Additional Features: Rear Only Gun Make: AR Platform Package Contents: Evolution Gun Works AR Bag Rider Rear Only Evolution Gun Works 32142: AR Bag Rider Rear Only Steel