This is a Magpul Industries Adapter known as the MS1, model MAG517-GRY.
Combine with the MS1 Sling and Paraclip(TM) to provide two to one-point convertibility. Manganese-phosphate finished steel and reinforced polymer hardware with custom snag-free high durability 1-1/4" webbing. Made in U.S.A.
Features:
Heavy-duty, push-button QD Sling Swivel
Strong and wear resistant
For fast transition between one-point and two-point configuration
