These inserts are for mid-2016 and newer cars that do not have threaded sections in the cross-member from the factory. They are comprised of a laser cut base plate with a pressed-in self-locking PEM for either 8mm or 10mm bolts.
 
Simply guide the insert into the existing slots of the cross-member and position for bolt insertion and tighten to spec with no tools! 
 
When ordering a new brace kit, these appear as an ordering option; these are available as an item to past brace kit purchasers prior to their introduction.