This is a Magpul Industries Sling known as the MS3 Single QD Sling, model MAG515-RGR.
Filling the same mission requirement as the standard MS3 Sling" the MS3 Single QD can quickly switch between one-point and two-point configuration. The MS3 Single QD maintains material construction and specifications identical to that of the standard MS3" but features a heavy-duty push-button QD Sling Swivel for the one-point (rear) weapon attachment rather than the Magpul Paraclip(TM). This modification allows compatibility with QD sling cups commonly found on lower receivers" receiver end plates" and buttstocks. The MS3 Single QD GEN2 incorporates a new low profile quick-adjust Slider which minimizes bulk and allows for secure" yet effortless" sling adjustment. Webbing length has also been increased for a comfortable fit with all body types and armor configurations. Made in U.S.A. and 100% Berry Amendment compliant.
Features:
Heavy-duty QD sling swivel for one-point attachment
Low-profile adjustment Slider
Allows fast transition between one-point and two-point