Magpul Industries Rail Sling Attachment, Fits ASAP Sling Plate, Black MAG502-BLK The RSA provides a low profile forward sling attachment point for the Magpul MS2 or MS3 and other clip-in systems. Made from nitrocarburized steel for wear and corrosion resistance" the RSA attaches to any 1913 Picatinny rail and has been proven to withstand stress tests of over 300 pounds while only weighing a mere 1.3 ounces. Made in U.S.A.