Mount Rail adapter with QD stud for Bipod attachment or swivel attachment. Needs a keyring type ring for slings. Fits onto Weaver type rails and enables the use of bipods or swivels where you were previously unable to use them. For use with 1/4inch wide Great for use on Quad Rail forends or other Picatinny accessory rails. Fits standard 20mm weaver and picatinny rail