FIND IT HERE! https://doublemdefense.com/product/mi-sbt-sling-adapter-for-stribog-sp9a1-brace/ 

Factory New.

SKU: MI-SBTSA

MI patent pending design
Features an anti-rotation QD Socket
Allows the user to mount a sling to the side folding SB Tactical Arm Braces
Constructed of 6061 aluminum, hard coat anodized with steel back up washers for a lifetime of service
100% Made in the U.S.A. with a MI Lifetime Warranty
Only works with the SB Tactical Braces: SBT, SBT5, SBT5K, SBTEVO