The Alpine Picatinny Rail QD/QR Rail adapters is milled with high quality metal. Offered in 2 styles: The QD/QR and QD adapters. The QD/QR 2 in 1 rail adapter converts to both style QD/QR styles. Just leave the center post inserted for QR or remove it for the QD style sling connection. Quick Disconnect (QD) and Quick Release or Pin style (QR). This rail mount is the only rail adapter you need for both QD and QR swivels. Comes in mat black coating for long lasting durability and performance.