Concur.  Good kit.

A good many users of QD, push-button, sling swivels find that the usual sockets allow unlimited rotation of the QD sling swivel within the socket/cup, and often this results in a tangled-up sling.

Before buying such a QD sling anchor point  (cup/socket), investigate whether or not the QD socket is  "limited rotation/anti-rotation".  You can check this yourself by simply plugging-in a QD sling swivel, and then attempting to rotate it within the QD cup.  It will be easy to determine whether the socket is of unlimited rotation or limited rotation type.   GrovTec makes them, as well as others: https://www.midwayusa.com/product/314136/grovtec-heavy-duty-push-button-sling-swivel-base-non-rotating-steel-black-pack-of-2

There are differing limited/anti-rotation cup/socket designs.  Some allow a varying number degrees of rotation, some lock into various places on the cup.  The GrovTec design allows the ball detent on the QD sling swivel to lock into 4 places within the cup, and so is a little bit more of a fuss to lock-in the sling swivel.  By their nature, limited/anti-rotation cups/receptacles are more expensive to make than similar unlimited rotation cups.

The limited/anti-rotation sockets require some thought regarding installation, so that the sling, when customarily attached to that socket, runs free, and is not affected by a limiting point in the socket preventing the sling from being deployed properly.  IOW, make sure you can turn the QD socket sufficiently, prior to locking it down in final position.  Check this by attaching the sling, and rotating the socket a bit until the sling "hangs" right.  Witness-mark cup and stock.  ONLY then lock the cup into place.

If QD sockets are already installed, and the socket has a bottom to it, then a possible answer is a rubber disc inserted into the base of the socket.  A small circle of rubber-like material will, if just the right thickness, add some resistance to the effort required to turn the sling swivel within the socket.  The thickness and "springiness" of the rubber disc is critical, as is the outer diameter-- use a hole punch.  When experimentation provides the correct thickness disc, use a small dab of adhesive to ensure it does not fall out.  There are anti-rotational QD sockets made, but if yours is/are already installed, then the above is the only answer, even if imperfect, that I know of.  This solution also serves to eliminate the rattle of the QD sling swivel against the QD socket.  Unfortunately, this suggestion soes not solve the problem encountered by QD sling users whose female receptacle has no bottom into which to insert the rubber disc.  If it's a simple, bottomless hole, no joy.

Knowing what I now know, I would strongly advise against buying/using/installing unlimited rotation QD sockets.  Compared to the limited rotation QD socket/cup they can be a PITA.   I expect that now that QD slings are becoming more popular, the mfrs of equipment that use such will make an effort to provide limited rotation sockets/cups on their equipment, and make limited-rotation QD cups more easily available for installers.

Interesting note is that when Col. Cooper specified flush, QD, sling mounts for his prototype Scout rifles, he used the (now-unavailable) Pachmayr sling mounts, which, when installed, were of non-rotating configuration.   The modern-day push-button QD sling swivel/cup is a less-costly to mfr/install design, and in some ways inferior to the old Pachmayr design.