This is a Accu-Tac Part known as the Sling Stud Rail Adapter, model SSRA-200.
The Accu-Tac Sling Stud Rail Adapter is designed specifically for its bipod line. The adapter allows you to use your sling stud to mount your Accu-Tac bipod. It is CNC machined" and coated with mil-spec hard anodize. Each rail also includes the necessary hardware for installation.
Features:
CNC machined
Hard anodize coating
